747b0392__5_1___Postgres_OnLine_Journal__Microsoft_SQL_Server_2008
[Feature] Case-Insensitivity - e.g. LIKE 'abc%' and LIKE 'ABC%' mean the same thing [MySQL 5.1] It is not case-sensitive by default but depends on character set (see comments from Giuseppe Maxia) [PostgreSQL 8.4] By default is case-sensitive , but in 8.4 we have newer contrib citext integrated to define case insensitivity fields. [Microsoft SQL Server 2008] 
By default its not case sensitive, but can change this down to the column level.
Cross Compare of PostgreSQL 8.4, SQL Server 2008, MySQL 5.1 - Postgres OnLine Journal
Microsoft SQL Server 2008