Hi,
SQL Server uses collations which specify rules on how character strings are compared and sorted etc. These collation settings can be set at the server level, database level or column level. The default collation settings for your server instance is specified during installation. This is usually Latin1_General_CI_AI which is not case sensitive. This will be used across all your databases and table columns unless specified. Therefore you cannot perform the action which you require (i.e. to insert 'auto' and 'Auto' into the primary key field).
In order to be able to perform this you could create a column which is case sensitive in your table by using the Latin1_General_CS_AI as shown below.
CREATE TABLE MyTable
(
[Code] varchar(10) COLLATE Latin1_General_CS_AS PRIMARY KEY
)
GO
You could also set a specific collation setting at the database level as well. Refer Books Online for more details on collation settings.
Hope this little explanation was useful...
Regards
Gogula G. Aryalingam (MVP - SQL Server)
