Working with Constraints
Constraints are rules that the database server enforces for you.
For details about working with constraints, see the following topics.
Ensure no duplicate values are entered in specific columns
Change the columns that the constraint is attached to, change the constraint name, or set additional properties for the constraint
Remove the requirement for uniqueness for values entered in the column
Create a constraint expression to check data for a condition
Apply constraints either to new data only or to existing data as well
Attach a check constraint to a table to specify the data values that are acceptable in one or more columns
Disable a check constraint when your table is replicated in another database
Disable a check constraint when data is added to, updated in, or deleted from a table
Change the constraint expression or the options that enable or disable the constraint for specific conditions
Remove the limitations on data values in a column
Show the properties for a selected check constraint in the Properties window.