SQL Server string constraints

Question

I have a SQL Server database with a time column which can only be filled with the text "am" or "pm" and I'm having trouble finding a constraint that would allow me to do this.

Answer 1

For SQL server you can use CHECK constraint which allows you to define a predicate that all the rows must meet in order to enter the table. Like so:

ALTER TABLE TableName 
ADD CONSTRAINT CHK_ampm
CHECK(ColumnName IN ('am', 'pm'));