Since the release of SQL Server 2005, Microsoft has been using what they call an Incremental Servicing Model for SQL Server. This means that every eight weeks, they release a cumulative update (CU) for a particular version and service pack of SQL Server. These cumulative updates typically have about 20-40 fixes, so they are somewhat like a mini service pack. One big difference is that cumulative updates do not receive a full round of regression testing like a regular service pack does. On the other hand, cumulative updates are released much more frequently than service packs, on a regular eight week schedule. There is some debate in the SQL Server community about whether you should apply cumulative updates or wait for full service packs. Many larger, more bureaucratic organizations only install regular service packs. I have had very good luck with cumulative updates over the last four years.
Here is a Build List for SQL Server 2005, 2008, and 2008 R2, showing all of the recent cumulative updates for the various code branches for each major version of SQL Server. If you install or maintain an instance of SQL Server, it is important that you also apply the correct service pack and cumulative update package for that version of SQL Server. This will help avoid many issues that have been fixed since the original "gold RTM" release of each version, which is what you get from the installation DVD.
Of course I should repeat the usual caveats about making sure you do your own regression testing of a cumulative update in your environment, with your own applications before you apply the cumulative update in a production environment. It is also a very good idea to read the fix list for each cumulative update to decide if any of the fixes look like they might be applicable to issues you are seeing in your environment before you decide to deploy that cumulative update.
You can run the query below to determine the exact build of any instance of SQL Server. The Build List will help you figure out what is installed based on the results of the query. If you have a build that does not show up on this list, that probably means that you have received an out-of-band hot fix from Microsoft Update.
-- SQL Version information for current instance SELECT @@VERSION AS [SQL Version Info]; -- SQL 2005 SP2 is now an "unsupported service pack" -- SQL 2005 SP2 Builds SQL 2005 SP3 Builds -- Build Description Build Description -- 3042 SP2 RTM 4035 SP3 RTM -- 3161 SP2 CU1 4207 SP3 CU1 -- 3175 SP2 CU2 4211 SP3 CU2 -- 3186 SP2 CU3 4220 SP3 CU3 -- 3200 SP2 CU4 4226 SP3 CU4 -- 3215 SP2 CU5 4230 SP3 CU5 -- 3228 SP2 CU6 4266 SP3 CU6 -- 3239 SP2 CU7 4273 SP3 CU7 -- 3257 SP2 CU8 4285 SP3 CU8 -- 3282 SP2 CU9 4294 SP3 CU9 -- 3294 SP2 CU10 4305 SP3 CU10 -- 3301 SP2 CU11 -- 3315 SP2 CU12 -- 3325 SP2 CU13 -- 3328 SP2 CU14 -- 3330 SP2 CU15 -- 3355 SP2 CU16 -- 3356 SP2 CU17
-- SQL Server 2008 RTM is considered an "unsupported service pack" -- as of April 13, 2010 -- SQL Server 2008 RTM Builds SQL Server 2008 SP1 Builds -- Build Description Build Description -- 1600 Gold RTM -- 1763 RTM CU1 -- 1779 RTM CU2 -- 1787 RTM CU3 --> 2531 SP1 RTM -- 1798 RTM CU4 --> 2710 SP1 CU1 -- 1806 RTM CU5 --> 2714 SP1 CU2 -- 1812 RTM CU6 --> 2723 SP1 CU3 -- 1818 RTM CU7 --> 2734 SP1 CU4 -- 1823 RTM CU8 --> 2746 SP1 CU5 -- 1828 RTM CU9 --> 2757 SP1 CU6 -- 1835 RTM CU10 --> 2766 SP1 CU7 -- RTM Branch Retired --> 2775 SP1 CU8 -- SQL Server 2008 R2 Builds -- Build Description -- 10.50.1092 August 2009 CTP2 -- 10.50.1352 November 2009 CTP3 -- 10.50.1450 Release Candidate -- 10.50.1600 RTM -- 10.50.1702 RTM CU1 -- 10.50.1720 RTM CU2
Here is the sequence of updates you would need to get current for each version of SQL Server:
SQL Server 2005, plus SQL Server 2005 Service Pack 3, plus SP3 Cumulative Update 10
SQL Server 2008, plus SQL Server 2008 Service Pack 1, plus SP1 Cumulative Update 8
SQL Server 2008 R2, plus SQL Server 2008 R2 RTM Cumulative Update 2
You can either apply each update in sequence, or if you are a little more ambitious, you can create a slipstream install that allows you to get on the latest CU with a single installation. Here are links to the latest service packs and cumulative updates for SQL Server 2005, 2008, and 2008 R2. Remember, you have to go to the correct web page to request a cumulative update from Microsoft. They will send you an e-mail with a password and a link to download a password protected, self-extracting zip file. You will also need to make sure to request the correct type of hotfix (x86, x64, or IA64).