SQL
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Ted Codd in the early 1970s. This version, initially called "SEQUEL" ("Structured English Query Language"), was designed to manipulate and retrieve data stored in IBM's original quasi-relational database management system, System R, which a group at IBM San Jose Research Laboratory had developed during the 1970s.
SQL Server Express
Microsoft SQL Server Express is a version of Microsoft's SQL Server relational database management system that is free to download, distribute and use. It comprises a database specifically targeted for embedded and smaller-scale applications. The product traces its roots to the Microsoft Database Engine (MSDE) product, which was shipped with SQL Server 2000. The "Express" branding has been used since the release of SQL Server 2005.