SQL Server 2005 How Create a Unique Constraint?
The SQL command is:
ALTER TABLE <tablename> ADD CONSTRAINT <constraintname> UNIQUE NONCLUSTERED ( <columnname> )See the full syntax here.
If you want to do it from a Database Diagram:
- right-click on the table and select 'Indexes/Keys'
- click the Add button to add a new index
- enter the necessary info in the Properties on the right hand side:
- the columns you want (click the ellipsis button to select)
- set Is Unique to Yes
- give it an appropriate name
In SQL Server Management Studio Express:
- Right-click table, choose Modify or Design(For Later Versions)
- Right-click field, choose Indexes/Keys...
- Click Add
- For Columns, select the field name you want to be unique.
- For Type, choose Unique Key.
- Click Close, Save the table.
ALTER TABLE [TableName] ADD CONSTRAINT [constraintName] UNIQUE ([columns])