This week we’re going to talk about a topic that has been gaining steam in the last few years and as it has it has started impacting database administrator’s worlds more and more: virtualization. Why do I make this statement? Well since the economy currently sucks, shops are finding ways to consolidate and make their dollars stretch a little further. Back in the day when you had a new application you pretty much went out and bought yourself some new servers and went on your merry way. Now, when money’s tight, folks are a little less likely to go out and simply buy new equipment for each individual application. Not only is this option expensive, there are other factors to think about such as space (data center may not have capacity for new servers), electricity and cooling.

Enter virtualization. Virtualization allows you to consolidate this server sprawl issue by buying a physical server, filling it with tons of your typical resources such as CPU, memory and drives, and from this single box be able to create virtual servers on this single piece of hardware that look/act/feel like independent servers. This week we’re going to cover some basics of virtualization and stuff you need to know about if you’re going to be going that route in your shop.

First things first, we need to familiarize ourselves with some basic terminology. These concepts are the same no matter what brand of virtualization so don’t worry about specifics. Later on we’ll dive into the different platforms/vendors and what they offer, but for now we’ll stick with general concepts and terms.

Host

Earlier I talked about buying a physical box to house your virtual machines on. This physical server is referred to as a host. The host contains all the physical resources that we will be allocating to our virtual environments including memory, CPU, networking and disks (I/O). Granted you can attach alternate methods of storage to your host, such as a SAN or NAS (which is common) for your storage needs, for these lessons we will refer to storage as being direct attached storage (DAS).

Hypervisor

The hypervisor is essentially a special type of Operating System, also referred to as a virtual machine manager/monitor, that is installed on the hardware (host) and its purpose is to present a platform between the hardware and the guest to allow multiple operating systems to share a single host and its resources. In a very simplistic way, think of the hypervisor as the traffic cop between each guest and the resources on the host. If multiple guests are asking for memory or CPU the hypervisor is the one that doles out the goodies to everyone in a quick and efficient way. The hypervisor is the “secret sauce” for virtualization and what makes all the magic happen.

Guest

When you create a virtual machine on your host, it is referred to as a guest. A guest, or virtual machine (VM), runs as an independent machine. The beauty of virtualization is that you can create a multitude of guests on a host, all running different operating systems. Once configured a guest VM looks/acts just like a regular server or machine on the network. Each guest can be independently configured with its own resources such as virtual processors, memory and virtual disks.

This is where you will be running SQL Server. When you remote desktop into this machine and go to control panel/device manager keep in mind you’re not seeing real hardware, you’re looking at virtual hardware that is presented to you via the hypervisor.

Abstraction

Technically this isn’t a virtualization term but it’s a concept you’re going to need to need to be really familiar with when virtualizing. Abstraction essentially means when something is presented in a simplified format but underneath it you have more complexity that is involved but you don’t necessarily have to worry about for your use. An example of this in the database world would be a view. You create a simple view that you can select from that looks like you’re selecting from a single table. In reality, that view’s definition is actually the joining of one or more tables together to get the result set for the view. By creating a view, you simplify the work for the end user by letting them query one “table” instead of having to do the work of joining several tables to get what they need.

Abstraction has you, Neo...

This concept extends over to the world of virtualization quite a bit. When you create a guest on a host, you create it with a certain set of resources. For example you create a virtual machine guest with 1 virtual processor that is 2.5 GHz and 2 GB of RAM (keeping this simple for now). The abstraction occurs when the hypervisor creates the guest, it creates it saying ‘you have X amount of memory and you have Y CPUs that are Z fast’. Behind the scenes, however, the host is doing something else. While the operating system on the guest says “I have 2 GB of memory”, the host is really only allocating as much memory as the guest needs at the time. So in reality the host is only allocating 128 MB of memory to that guest at that given time. The 2 GB you “gave” the guest, can almost be viewed as a more of a max memory option.

If the guest becomes really active and requires more resources, the hypervisor gets this request and allocates those resources from the host and subsequently passes it to the guest, up to the maximum of what you allocated to the guest. During all this process, the guest is never made aware of any of this shenanigans going on behind the scenes. It’s simply a server with 2 GB of memory doing it’s typical routines! Now, on a simple system you may never notice any performance issue with this, and a good hypervisor makes this situation seamless as you should never really see the effects of this process affecting your performance…until you do.

This also occurs with processing power as well. We gave our guest one virtual processor that runs at 2.5 GHz, so we’d expect if we were to run a process that is CPU intensive, that CPU would be running at speed of 2.5 GHz. Again, an administrator has the ability the throttle these resources so from the hypervisor so while activity monitor within your guest can show 100% utilization but on the host side, the CPU can really only be 25% utilized.

This is where understanding what resource allocation and abstraction becomes crucial in architecting a proper virtualization environment. Now that you’ve understood some of the core concepts, in our next lesson we’ll talk about how SQL Server fits into this whole picture and what you need to account for to ensure your virtualization project goes well.

[NOTE] My blog post scheduling-fu is weak, so this post didn’t go out Friday as planned. My apologies.

This is the final installment of our Small Business series. So far we talked about how to get the software, and we’ve talked about the different options of SQL Server available to you. Today we’re going to talk about what hardware you’ll need as a small business to setup your database environment for success.

Backups, Backups, BACKUPS!

Before we even start getting into hardware for your database servers, answer this question: Are you taking backups? I’m not only asking about SQL Server backups (which you REALLY need to be doing), but backups of any and all of your data as well. There are tons of options for backup devices out there, I highly recommend you add this to your shopping list if you’re putting together hardware list for your budding IT department. I lead with this advice because we can setup the most awesome server setup in the galaxy but it doesn’t do you a bit of good if the power goes out suddenly and all of your databases get corrupted and you have no backups to restore from! If you’re unsure of what sort of backups and maintenance you need to setup for your databases, don’t sweat it, Brad McGehee (Blog | Twitter) wrote a great (and free) e-book on setting up SQL Server Maintenance Plans that I highly recommend you get/read right now. You can also check out Ted Kruger’s HA/DR week from last semester to help you wade through your options.

I can’t emphasize enough how important backups are in your environment, ESPECIALLY in regards to SQL Server. Your data is the lifeblood that powers your business, without it you’re dead.

UPS

As much as I’m a fan of the folks in the ugly brown uniforms, I’m not talking about the delivery service here. UPS stands for uninterrupted power supply. Basically this is a giant battery that you’re going to plug your critical equipment (i.e. servers, routers) into and then plug the UPS into the wall. What happens is that when the power goes out you’re the UPS will continue to power your equipment off its battery until either the power comes back on or you manually shut down the servers yourself. Again, there’s a slew of UPS options out there you can purchase.

There’s a few things to watch out for here, however. UPSes come in all sizes and capacities. The smaller the size, the less battery capacity it has and the less load it can handle. Also because of the different capacities and sizes, that will affect how long it can run on battery before the UPS dies out as well. I mentioned that when the power goes out you’ll need to time to manually shut stuff down. Well UPS systems can’t run forever and the power outage may only be a few minutes or it can last way longer than your system can handle running on batteries. When the outage is going to exceed your UPS’ capacity, start shutting down your systems manually. During this period it will let you save anything pertinent and gracefully shut down systems such as SQL Server. Do NOT try kicking off full backups or anything extremely intensive when your switch to running off the UPS as the more workload you put on the server, the more power it is going to need from the UPS and the less time you’ll have running off batteries. So again, just make sure you have sound backup strategy in place.

Servers

Ah finally, the hardware. Like with everything else, you’ve got quite a few options in this department. I’ll lead off this section by pointing you to a fantastic resource in the SQL Server hardware department and that resource’s name is Glenn Berry (Blog | Twitter). Glenn wrote a fantastic book, which Brent Ozar wrote up a great review on, that covers EVERYTHING you need to know to choose the right hardware to run SQL Server on. I won’t go into specific details about what you “should” be using, because it differs for everyone. Again, there are many different options out there but I’ll just do an extremely high-level overview of a few options.

Desktop/Tower Servers – Okay a server is really nothing more than a regular machine on your network with some specialized software running on it. Technically you can fire up a Windows XP laptop, enable IIS on it and call that a server (I really wouldn’t recommend this as a production solution, by the way). Desktop/tower servers, or rather machines that are essentially running on what look to be regular desktop equipment, have a few differences compared to your regular desktop machines. One of the main differences is that there isn’t only one hard drive in these machines. If you fire up a desktop server you may only see a C:\ drive but behind the scenes you’re probably really looking at two or more hard drives setup in a RAID array.

In small businesses and offices, it’s often common to go with a tower/desktop as a server due to costs or simply space. With a tower you can just set it up under a desk or tuck it in a corner somewhere. While this is a relatively easy setup there are a few issues you should be aware of. If you place a tower server on the floor somewhere, especially under your desk for instance, you could risk accidental damage like kicking it or spilling your morning coffee on it. Probably not the best thing for electronic equipment! Also tucking a machine like that underneath or behind something you run the risk of overheating, which can be really bad for the system.

Another fun issue I’ve seen in small business before is someone plugging in vital equipment (such as server or router) into a wall socket that is controlled by a light switch. I know someone who worked at a company that noticed everyday around 5 or 530 their entire network would go down. It turns out that the last person leaving the office was flipping off the light switches and one of the routers was plugged into it. Once they turned off the lights, they turned off the router which brought down their entire network. Fun times.

Rack-mount servers – These are the servers you typically see in a data center. The obvious drawback here for small businesses is that you would need to buy the rack in order to support these types of servers. On the flip side, if your company has need for multiple servers then buying rack and going with rack-mount servers is probably the better bet. I say this because the tower servers can be cumbersome in regards to finding space to store them. The other nice thing about rack-mount servers is that they’re elevated off the floor so the hardware is protected by things like flooding (unless your UPS is also on the floor then you might run into issues).

Racks are also great because it just makes things more organized. Typically you can mount power strips along the back and also put in other equipment such as network routers in with the servers, so everything is organized nicely in a single space. Also they make rack-mounted UPS units so again, big win for everyone! The obvious drawback for rack-mounts is that the rack needs a place to go. Typically you setup a rack in a dedicated closet or room somewhere in your office.

A few things to note when setting up servers in your closet/server space, YOU NEED COOLING! This hardware is up and running 24/7 and it will generate heat. Make sure you take this into account when selecting your hardware setups and locations.

Storage

You’ve got your horsepower now you need somewhere to keep all that data. Again, a few options here. Direct attached storage (DAS) is the most common form of storage and the one you’re probably used to. That drive in your laptop now? That’s direct attached storage. One, lonely spinning wheel of magnetic death. While this option may be cheap and easy, don’t skimp on your business. If you’re going to do DAS then protect yourself and setup the proper RAID groups. Since we’re focusing on SQL Server here, check out this Storage Top 10 Best Practices article from the SQLCAT team.

To get a good overview on storage, check out Brent Ozar’s SQLU Storage Week posts, which while we’re focusing on small businesses this week, still apply across the board no matter what size company.

The Cloud

Really, this again? Yeah, this again. I’m telling you, Cloud strategies are more than just marketing fluff, it’s an extremely viable and cost-effective solution especially for small businesses. All that stuff we’ve covered today, all of that is handled in background for you if you decide to instead have your infrastructure hosted using a cloud solution like Windows/SQL Azure.

So class, is there anything else you think is missing from this small business puzzle? How is everyone doing on their homework assignment from last class? Let me hear from you in the comments!

In our last session we talked a little bit about the different options you have in regards to SQL Server in your environment. We talked about HOW to get the software but now we’re going to talk about what the different editions are and what they offer you. For a quick comparison between editions you can use the Edition Comparison page at the Microsoft site. As a small business you’re looking to get the best bang for your buck. You also want to make sure that whatever decision you go with, you can easily scale up so your infrastructure can grow as your business does. Thankfully, SQL Server’s growth scale is pretty easy. We’re going to cover editions from the lowest level up.

Express Edition

This edition of SQL Server is free, which is great especially if you’re looking to get your feet wet developing on the platform and don’t have/not willing to put down the cash for a license just yet. Express edition is great if you’re looking to build small-scale applications or small desktop applications. Great thing about this edition is its also portable so as an ISV (Independent Software Vendor) you can actually create an application using Express Edition and bundle it with your own software.

The drawbacks for these lower editions come in the restrictions. For Express Edition you are restricted to 1 CPU, 1 GB memory utilized and the databases have a 10 GB size restriction. If you do decide to go with this and you find that it is too restricting for your needs, you can easily upgrade your instance to the next level up which is Standard Edition.

Compact Edition

Compact Edition is also a free edition of SQL Server however you won’t ever be running anything (read also: infrastructure) from your business off this. Why did I include this then? Well, there are small businesses out there that develop software for clients that are mobile or occasionally connected employees (think travelling salespersons). Compact Edition gives you the ability to create software and embed a database inside the application. This edition gives you the ability to use SQL Server on a small-scale and distribute with your applications for free.

Workgroup Edition

Workgroup edition is much less restrictive than Express edition, however this is edition you have to pay for. At this level you start getting more protective features such as Log Shipping, something that Express doesn’t offer. Also your restrictions go way up here as this edition supports up to 4 CPUs, 64 GB of memory and the database size limitation goes up to 524 PB! Also on the administrative side, you get the ability to use the SQL Agent which allows you to automate jobs on a schedule. This also allows you to create maintenance plans, use Database Mail and use Performance data collector (2008 R2 feature).

If you look at the pricing for this edition it is pretty close in price to Standard Edition, which makes me wonder why they even bother offering this as an option since they’re clearly trying to steer you towards Standard! This may not necessarily be a bad thing as Standard Edition is going to have everything you’ll need to get started but it just makes things kind of confusing for everyone when you offer so many options to begin with.

Web Edition

This is geared more towards the shops that will be using SQL Server on a public-facing website. This is important distinction to make as the licensing terms between this and some of the other higher-level editions (i.e. Standard, Enterprise) are different. For instance if you’re using SQL Server Standard edition internally and only 10 people/devices will be connecting to it, you can purchase individual CALs (Client-Access Licenses) at a much lower cost than a per processor license. A per processor license allows for unlimited connections to the target server. The Web edition’s license is only available on a per processor basis but its per processor cost is much lower than that of a Standard Edition but still offers pretty much the same feature-set as that of Standard. These types of distinctions are important to make as you want to make sure your company is properly aligned license-wise for your uses. Again, you can check out the Licensing page to get a quick look at each edition’s list prices for comparison.

Standard Edition

This is more than likely where most companies end up starting off at as far as choosing SQL Server for infrastructure use. Standard Edition offers a pretty comprehensive list of features, which you can check out here on the Features Supported page. Standard Edition is going to give you not only the full power of SQL Server but also the protection you need as a business in that it offers protective features such as database mirroring, log shipping, backup compression (the other editions do backups but don’t do compression, if you’re looking to save on disk space this is nice option to have), replication, automation, much more.

As a small business there are a few things you need to make sure you’re doing to protect yourself, namely backups (if you don’t do anything else, please PLEASE setup backups!!!) and general maintenance. Not sure what you need to do for either of those? Make sure you check out the Administration and High Availability/Disaster Recovery posts at SQL University to help give you some direction.

SQL Azure

SQL Azure is the new kid on the block and brings a whole new dimension to how you can use SQL Server in your enterprise. So far all of the editions we’ve discussed require you to not only purchase the software, but you’ll need hardware to set it up on! With SQL Azure those headaches are removed as Microsoft hosts your database instances for you in their data centers so you get the power of SQL Server plus the peace of mind that your databases and applications (they offer Windows Azure as well) is backed by an extremely robust and scalable infrastructure. In addition, they’ve started rolling out other nice features like Reporting Services and Data Sync. Data Sync is really cool as it allows you to sync your cloud databases with those already in your local environment. Please note both of these features have not been rolled out to production in Azure yet.

The other nice thing about Azure is that the pricing model is much different from what we’ve discussed so far. With Azure you pay for usage/data consumption rather than worry about processor licenses and all of that stuff. You can check out their FAQ page to answer a lot of questions you may have about this exciting new emerging offering. You can also check out their cool Pricing Calculator to help you figure out what your costs would look like.

As cool as Azure is, it’s not all unicorns and rainbows folks. Unfortunately there are feature limitations in Azure that may make this a deal-breaker for your company. You can see the full list of Feature Limitations here. Now before you read the list and freak about Backup/Restore and Replication not being supported hear me out: Azure is already doing both of those things for you in the back-end, hence you don’t need to handle it yourself. Buck Woody (Blog | Twitter) will be covering Azure more in-depth this semester or can check out this blog for everything you need to know.

Conclusion and Homework

Bottom line is there are many options available to you as a business to use SQL Server, the big question is what works right for you. Also bear in mind that you don’t have to just have one edition, you can mix and match to your heart’s content. Have a web application but you need to host it on-site? Get a web edition license and put it on a web server in your office. Need that same website to scale and not have to worry about infrastructure? Move it up to Azure. Have multiple applications that require SQL Server but each application has certain patching restrictions? Buy a standard edition license and create named instances all on one piece of hardware.

Your homework for this assignment is listed below. To complete this assignment post your response here or write up your own response blog post and link your post in the comment section below.

• Figure out a licensing scheme for this fictitious startup company that has the following requirements -
• Public-facing website that will handle light to moderate traffic at first. Must be able to scale in case demand ramps up rapidly.
• This company develops software so would like to have a development, QA and production environment if possible.
• Sales division has people that have mobile devices with partial copy of sales database on them. They need to be able to sync data up when they come back in to the office from the field. If possible, sync while on the go.
• Need to be able to automate routine maintenance such as backups for all critical databases in-house.

Welcome back to SQL University! This week we’re going to be discussing architecture. In previous weeks we’ve discussed architecture at a high level (Capacity Planning Week) but this week we’re going to get a little more focused. SQL Server is used by businesses of all sizes from local grocery stores to large-scale sites like MySpace (Case Study) or GoDaddy (Case Study). So why are we focusing on architecture for small businesses? The reason is that if you’re expecting for your grow and expand, making the right architectural choices up front can help reduce the headaches that come with potentially rapid growth.

Software and Licensing

Before you start you developing on SQL Server you’ve got to get the SQL Server software! There are several editions and options you can go with. Depending on your company’s IT budget, you’ll need to make certain allowances and choices in regards to what edition of SQL Server you’ll go with. There are several editions of SQL Server that I’ll categorize as “entry-level” listed from the most basic to the more advanced (read-also: more features):

In Wednesday’s class we’ll dive deeper into what the differences between each edition are their pros and cons are. For the purposes of today’s discussion we’re simply listing them out so you know that there are several options available to you. What we’ll discuss today is how you go about getting said software to help you get started. The first couple of editions listed, Compact and Express, are available as free downloads directly from the Microsoft website. The other editions are paid editions that have several options of getting them. To see a quick price check/comparison, use the ‘Which Edition?’ section on SQL Server licensing page.

Microsoft has a special program created specifically to help getting small businesses setup with software called BizSpark. What is BizSpark? In their own words:

Microsoft® BizSpark™ is a global program that helps software startups succeed by giving them access to Microsoft software development tools, connecting them with key industry players, including investors, and providing marketing visibility to help entrepreneurs starting a business.

Once you get signed up for BizSpark you’ll get access to Microsoft’s developer software subscription service, MSDN. Development software you’ll have access includes Office suite, Windows operating systems (Server and Desktop), Visual Studio, SharePoint Server, BizTalk, Exchange Server, access to Azure (Windows and SQL Server) and yes, SQL Server itself as well. This program is great small companies getting ramped up and you can review all the details over at their FAQ page.

The next important part is licensing. The MSDN subscription gives you license keys but eventually you’ll need to budget for software licenses for your business. You can get a rough estimate of licensing needs by using Microsoft License Advisor tool on the Microsoft Volume Licensing website. Don’t be started by the numbers you see/get. Those are retail prices and are usually negotiable for businesses and such. For the most accurate help in licensing I highly suggest you contact your local Microsoft office as they’ll have someone available to you to help navigate licensing agreements that help best fit your particular needs.

SQL Server Licensing

In regards to SQL Server licensing there are a couple of ways you can purchase licenses:

• CAL (Client/Access License)
• Per Processor

The simpler (but more expensive) choice is using the per processor model. Purchasing a license per physical processor allows you to have unlimited connections for both users and devices to your server either inside or outside your firewall. This option is available for Datacenter (required), Enterprise, Standard, Workgroup, Web (required) and PDW (required) editions. Your other option, and the one most likely to make sense for a small business, is the Client Access License (CAL). CALs require that you buy a license for each device and/or user accessing or using the functionality of SQL Server or any of its components. This option is more beneficial if you are able to count the number of devices/users connecting to your SQL Server and that the number of users/devices is low enough that its more cost efficient than the per processor option. You can read more on these details from the SQL Server Licensing Quick Reference Guide (PDF).

To The Cloud!

Does your head hurt yet? I don’t blame you and you’re definitely not alone, these things can get complicated and annoying real fast. As you can see, simply choosing licensing and software can get convoluted and confusing, and we haven’t even installed anything yet! Enter: The Cloud. Last semester Buck Woody (Blog | Twitter)  introduced us to Cloud Computing and what benefits it could bring. Depending on your particular needs, SQL Azure (the cloud offering for SQL Server from Microsoft) may be exactly what you need if you want the power and ease of SQL Server without the administrative headaches and overhead. SQL Azure will be covered more in-depth later on this semester but for the time being go check out the SQL Azure website for more details. Also some more recommended reading, check out Andy Leonard’s (Blog | Twitter) post today about The Sky is Falling to get another viewpoint on the Cloud offering.

In our next lesson, we’ll go more in-depth in to the different editions of SQL Server and what each one brings in terms of benefits. As a small business you want to make sure you make the right choices for your needs, but also want to make the best cost-effective decisions for the long haul. In addition to software, we will be discussing hardware and infrastructure choices as well later this week. Your assignment for this class is the following:

• Read the various resource links used in this post
• Respond to this question either here in comments or write up your own blog post and link it here: “Do you have or work for a small/medium size business? If so, what are your current licensing strategies? If you don’t, share with the class how your company (if you know) does it.”

Welcome back, class! In our last class, we setup a parent-child package configuration and showed how you can pass variables between the two in order to complete a unit of work. In today’s class we’re going to continue exploring that data load package and take a look at another critical piece of SSIS that you should know about: precedence constraints.

So what exactly are precedence constraints? They are the connectors that link together tasks in the Control Flow, and they define the workflow of your package. When two tasks are tied together with a constraint, the destination task will execute based on two things: The final state of the task that precedes it and special rules you can define on the constraint using specialized expressions.

Constraint Types

You can have different types of constraints between tasks. You can read more about constraints in detail from MSDN article (Link). I’ll briefly cover each of the constraint types in an abbreviated list and then we’ll discuss how we used these constraints in our parent-child package from our previous lesson.

• Success – Workflow will proceed when the preceding container executes successfully. Visually indicated in control flow by a solid green line.
• Failure – Workflow will proceed when the preceding container’s execution results in a failure. Visually indicated in control flow by a solid red line.
• Completion – Workflow will proceed when the preceding container’s execution completes, regardless of success or failure. Visually indicated in control flow by a solid blue line.
• Expression/Constraint with Logical AND – Workflow will proceed when specified expression and constraints evaluate to true. Visually indicated in control flow by a solid color line along with a small ‘fx’ icon next to it. Color of line depends on logical constraint chosen (e.g. success=green, completion=blue).
• Expression/Constraint with Logical OR – Workflow will proceed when either the specified expression or the logical constraint (success/failure/completion) evaluates to true. Visually indicated in control flow by a dotted color line along with a small ‘fx’ icon next to it. Color of line depends on logical constraint chosen (e.g. success=green, completion=blue).

Note: In these screenshots there are labels next to the precedence constraints indicating the type of constraint chosen. This is not a default behavior. To enable this click on Tools menu, go to Options. Under Business Intelligence Designers, go to Integration Services Designers and under the Accessibility section in the General menu, check the box for ‘Show precedence constraint labels’. This is helpful for folks who are color blind and are not able to differentiate between green/red/blue lines in designer. Big thanks to Dan English for this great tip.

Constraints in Action

Now that we’ve seen the different constraint types, let’s examine how they’re used in conjunction with parent-child package setup. Our first use of constraints comes at the top of the child package from the script task to the sequence containers. We’ve used an empty script task as an “anchor” task. This is used as a starting point to continue on to the corresponding workflow. As we learned in our last class, we have a variable being passed from our parent package with the value of the name of the file we are currently processing.

In this first example, we’re going to look at the constraint leading to the sequence containers for the Supplier table. We’ve used and Expression and Constraint here and chosen the value for Success. We’re also looking at the value of the variable being passed to the child package. For this particular workflow, we are waiting until the value of the variable ‘Parent_TblName’ is set to “supplier”. Once both of these situations evaluate as being true, we will execute this container.

Now that we’re inside our sequence container, we have another set of constraints. Once again we’re using an empty script task as an “anchor” for our precedence constraints. This time we’ve got two possible paths to go down. The first is to execute an Execute SQL task. This task checks for the existence of the table (in this case, the supplier table). If it exists it will drop the table and then recreate it. The other path leads directly to a data flow task which simply loads the table specified from the flat file.

I’ve created another variable on this package called ‘AppendFlag’ which is a boolean value. The purpose of this flag is so that you can choose to load the tables with a fresh load from the flat file (the Execute SQL task path) or you can simply append an already existing table’s data with data (data flow path). The default value of the variable is false.

The first path to the Execute SQL task uses an expression and constraint which is looking at the value of the ‘AppendFlag’ variable. In order for us to go down this workflow both value of ‘AppendFlag’ must be false AND the previous component executed successfully. The other path from the script task leads directly to the data flow task which actually loads the table. For this path, I’ve set the precedence constraint to look for the value of ‘AppendFlag’ to be true. In this path, however, we’ve chosen to use a logical OR. The reason for this being that the Execute SQL task, once complete, also leads to the data flow task. Due to the data flow having two different input paths, we must use the logical OR (if you try to choose logical AND, BIDS will quickly yell at you).

Conclusion

When we bring it all together, we now have a parent-child package that passes variable values. These values are used to execute specific workflows based on the value of the variable passed. Precedence constraints are an extremely helpful and invaluable tool in your SSIS toolkit. Using precedence constraints can help you create very dynamic workflows within your packages.

Welcome to the second week of SSIS this semester at SQL University. Today we’re going to talk about the relationship between children and parents. Ever had communication issues with your kids when you ask them to complete a chore? When they’re done, wouldn’t it be nice if they always came back and let you know they took what you said, applied it, and completed the job? What does that have to do with SSIS? Read on and find out!

As parents sometimes you have a large task to accomplish and you need the whole family to pitch in and help out. In SSIS we can accomplish something similar by setting up packages in a configuration we call (wait for it) Parent-child packages. Original name, eh? In today’s example we’re going to look at a parent-child package setup I’ve created that loads generated data into their corresponding tables.

As the task executes and looks through the designated target folder, it will take the name portion of the file without the extension and populate a variable called TblName with that value (i.e. The value for orders.tbl is simply ‘orders’). This step is important in this case as we will be utilizing this variable in our child package to perform our processing.
Once the variable is populated we’re going to execute our child package called, originally enough, Child Package!

Child Package at a Glance

So how does the child package get to see that variable’s value anyways? I’m glad you asked! In order for the child package to be able to “see” this value getting passed, we have to do two things: The first is to create a variable in this package that will hold the value passed from the parent. For this example I’ve created a variable in the child package called ‘Parent_TblName’. Note that I used the same name only I preceeded it with ‘Parent_’. The name of the variable does not have to match in order for this to function, however, using this naming convention helps you quickly identify the fact that this variable is being used to hold the value from another package. Also, while the name does not have to match that of the variable in the parent package the data type does. Make sure both variables have the same variable type.

Variable in Child Package

Setting Up Parent Package Variable

Connecting Our Variables

If you’d like to download this package to study the components, you can download the project solution files here

This week SQL University is on Spring Break but we’ve lined up some activities to help keep students busy (you know what they say about idle hands and whatnot!). In continuation of Women’s History Month, and properly coming off of the heels of the 24 Hours of PASS event, we’re proud to have our next talks in our Lecture Series this Friday at 1pm EST featuring the ladies of WIT Week here at SQL University.

Our Live Lecture will be happening over at SQLLunch, and as always it’s free, so make sure you go register for the event. If you enjoyed reading all of the fantastic posts from WIT week you’ll love this event. The session is going to be a round table discussion about what WIT means to them as well as discussing some of the issues they’ve faced and would like to address in the field. Audience participation is encouraged via Q&A in LiveMeeting so come join the panel. See you at the SQLLunch!

The new SQL University Logo

Well the new year is here and SQL University is back and better than ever! I just wanted to take a minute to bring everyone up to speed on what’s going on with SQLU.

First off the last semester we had (Spring 2010) started rather late, which pushed the rest of the schedule quite a bit. One of the unique facets of SQL University is having our coach Tom LaRock (Blog | Twitter) posting on EVERY topic, EVERY week which is quite the impressive feat! That being said, since the last semester ran a few weeks late it not only made a lot of work for him so I wanted to give him ample time off as that is a TON of writing he’s doing, which I think we can all agree, is pure awesomesauce. Also Tom has undergone a job transition, as well as I have, so it’s been a little hectic on that front as well. Due to the schedule shifts, job changes, moves and generally hectic life we decided to skip the Fall semester for 2010, hence you’ll find it missing from the overall SQLU main page.

Another reason we went quiet for awhile was we were busy putting together another major project: SQL University – The Book! No, sorry, no movie deals in the works but I think you guys will like this even better. What we’re doing is compiling all of this awesome material our professors have put together for you guys into an organized e-book companion! My hope is that we can it formatted properly for distribution via Amazon’s Kindle store but if that doesn’t work out we’ll probably just PDF it and let you guys go to town! As with the rest of this wonderful project, this is absolutely free to everyone and will be released as SQL University: Volume I, Freshman Year which includes the first two semester’s worth of blog content! This is taking a lot of time to put together so bear with us as we get that worked on.

Another big change you may have noticed, and one of the most exciting parts about this new year, is our re-branding! Our new logo comes courtesy of the wonderful folks at Revealed Design Inc. (Facebook| Twitter) and a big thanks to Aaron Nelson (Blog | Twitter) for hooking me up with them. This is a much cleaner design and look than my atrocious attempt at designing a blogger badge from before. When you visit each professor’s sites this time around you should see the new badges displayed.

Finally the other huge addition this year is our partnership with SQLLunch.com to bring you the live lecture series. We had our first one featuring Josef Richberg during SSIS week. We’ll be bringing you more this semester with some big names so stay tuned! The best way to keep up to date on all the latest news and additions to SQL University is to join our newsletter.

One More Thing…

If you’re enjoying SQL University and learning from all of these great folks in the SQL community you’ll get a chance to experience all of this in person! This Spring at SQLRally we’ll be hosting a Lightning Talk session featuring the professors of SQLU as well as some other special surprise guests. SQLRally runs from May 11-13 in Orlando, Florida and only costs $299  and $199 for pre-conference sessions (optional). Hope to see you there!

The new SQL University Logo

Welcome back students! We’re very excited to start up a new semester and SQLU is back and better than ever! This semester we’re lucky to have 7 MVP’s, 7 Women in Tech (most ever!) and a Microsoft Certified Master (MCM) in SQL Server presenting topics. In addition to our regular lessons we have the SQL Rockstar himself, Tom LaRock (Blog | Twitter), hosting weekly DBA Coaching lessons on his blog as well. Our staff is also hard at work putting together an e-book compilation of the first two semesters-worth of content. We’re calling this compilation SQL University Vol 1: Freshman Year. As soon as we finish putting it together we’ll announce it via the mailing list along with communications on Twitter (Follow us @sqluniversity). What mailing list you ask? Well if you want to make sure you get all the latest news and updates for SQLU please sign up for our mailing list here.

Semester Schedule

We’ve posted the semester’s schedule at our main page,http://sqlchicken.com/sql-university, make sure to bookmark that page and check back regularly as all lessons will be posted there. Any changes to the schedule will be sent out to the mailing list as well as update that page. Here are the weekly topics as well as the professor teaching it that week for this semester. Another small but subtle change this year is we’ve started placing icons next to the professors names that indicate various awards/recognition such as Microsoft MVP’s, Microsoft Certified Masters (MCM) and winners/finalists for Redgate’s Exceptional DBA of the Year award.

PowerShell I: Aaron Nelson (1/18/11)

Advanced SSIS: Josef Richberg  (1/24/11)

Reporting Services: Jes Borland (1/31/11)

Security: K. Brian Kelley  (2/07/11)

Data Warehousing: David Stein (2/14/11)

Professional Development: Andy Leonard  / Ted Krueger  (2/21/11)

Administration: Mike Walsh / Robert Davis  (2/28/11)

Women in Technology: Audrey Hammonds / Jennifer McCown  / Jes Borland / Julie Smith / Wendy Pastrick (3/7/11)

SPRING BREAK (3/14/11)

• No classes

Storage: Denny Cherry  (3/21/11)

Cloud Technology: Buck Woody (3/28/11)

Performance Tuning: Grant Fritchey  / Ted Krueger  (4/04/11)

Administration VLDB: Mike Walsh / Robert Davis  (4/11/11)

High Availability/ Disaster Recovery: Geoff Hiten / Robert Davis  (4/18/11)

PowerShell II: Aaron Nelson / Grant Fritchey  / K. Brian Kelley  (4/25/11)

Advanced SSIS II: Jorge Segarra (5/02/11)

Analysis Services: Stacia Misner (5/09/11)

Internals: Erin Stellato (5/16/11)

Troubleshooting: Dave Levy (5/23/11)

Again thank you all for your support and following along with SQL University! If you have any feedback or suggestions please fill out our Survey Form.

In the first part of this week’s documentation series we covered documentation in the traditional sense. In today’s lesson we’re going to talk about a new avenue which many are using as a sort of documentation repository and that is the personal tech blog.

Now I could use this lesson as an entire post on how to get started blogging but I won’t. Instead I will re-direct you to professor Brent Ozar’s series on How to Start a Blog. Consider that your homework assignment for this class. So if I’m not going to talk about starting a blog then what are we going to discuss? How about the significance of blogging or writing for your own personal development and growth? I’m very fortunate in that I have managed to have Tom LaRock (Blog | Twitter) as part of the faculty and this semester he is playing the role of DBA Coach and he touches on some of these points in this week’s lesson as well.

Help Yourself

So this is documentation week, what does that have to do with blogging? Well, let’s say you’re a small company. You’re the one-man show in the IT department (in fact, you ARE the IT department). Since you’re tasked with trying to do anything and everything it gets really tough to remember how you fixed that one problem on that one system many months ago. Now since you’re just one person, chances are you don’t have something like Track-It! or CA Service Desk to log trouble tickets and create a knowledgebase with. So what do you do? Well you can hope you can remember everything or you can start documenting these things. A blog is a great place to document these issues as you can easily refer back to them at a later time. There are plenty of free blogging platforms out there such as Blogger or WordPress that make starting one a breeze. In addition to making it easy, they provide plenty of tools to help you get started. For me, I started on Blogger as the interface was extremely user-friendly and since I already had a Google account I was up and running in a matter of minutes. In addition to nice tools for content creation, you have nice built-in search tools so if you’re somewhere and need to look up ‘arcserve fix’, your site is already to receive that query and find the posts for you that fulfill that request.

Help Others

Since your blog is public (by default but you can make it private if need be), search engines such as Google and Bing can index it. The power behind this is that sometime, somewhere somebody is running in to the same issue as you. And when that happens, what’s the first thing people do? They Boogle the problem. And if you’re thinking “I’m running some obscure software that nobody else runs” then all the more reason to blog your solutions for the world because I guarantee you that a company wasn’t formed, developed a software package and sold one and only copy of it (unless this is stricly a custom homegrown app but you know what I mean). How many times have you done a search for something and you get the dreaded ‘no results found’ page? Well aren’t you glad that everytime you search for something and hits are returned that you have something to go to? Well, now you can help seed that global knowledgebase! Best part about having it public is that if you’re a consultant (or at a relative’s house which you inevitably get sucked into helping because you’re the “computer” guru of the family)  you can always get to what you need from your site. Also helps when referring others. Let’s say you get asked about a particular issue all the time. Instead of having to answer each email individually, and having that siphon your time, just write up a post addressing the issue and direct folks there. Eventually when they see you have something to offer they’ll keep coming back, you keep writing and everybody wins!

For Friday’s class I’ll be talking about tools to help you in your documentation efforts. In the meantime make sure you read the assigned reading from above and see you guys at the next lesson!

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