Released builds can be found here on the Microsoft website.
A self maintained page for SQL Server Express builds can be found here.
Microsoft currently releases 3 main types of SQL Server patches and these are:
- Service Packs (Discontinued starting with SQL Server 2017)
- QFEs (CUs)
Service Packs are typically applied to all instances of SQL Server, if supported by the application and if testing in a non-Production environment reveals no issues.
- From SQL Server 2008 onwards, the SQL Server Service Packs can be uninstalled, unlike previous versions where re-installs of SQL Server were required if an issue occurred.
- From SQL Server 2017 onwards, the SQL Server Service Packs have been discontinued. CUs will be delivered more often at first and then less frequently. Every month for the first 12 months, and every quarter for the remainder 4 years of the full 5-year mainstream lifecycle.
GDRs (General Distribution Release) are typically released between Service Packs to address issues of importance e.g. a security vulnerability. As with Service Packs, GDRs are typically applied to all instances of SQL Server, if supported by the application and if testing in a non-Production environment reveals no issues.
QFEs/CUs (Quick Fix Engineering/Cumulative Updates) are hotfixes which address specific SQL Server build issues. QFEs typically get consolidated and released as CUs and the CUs in-turn get consolidated and released as a Service Pack. The key difference between QFEs/CUs and Service Packs is the amount of testing performed by Microsoft. Service Packs are more rigorously tested and therefore it is recommended that QFEs/CUs should not be applied unless they address a specific issue being experienced.