Adding column-level constraint to a column

You can declare a check constraint to limit the values users insert into a column in a table. Column-level check constraints can reference only the column on which the constraint is defined; they cannot reference other columns in the table. To add a column-level constraint:

Select the column.
Select Properties.
Select the Check Constraints tab.
Select Add. Follow the instructions on the Add check constraint wizard to add a check contraint.