Modify Unique Constraints

You can modify a unique constraint in SQL Server 2012 by using SQL Server Management Studio or Transact-SQL.

In This Topic

• Before you begin:

  Security

• To modify a unique constraint using:

  SQL Server Management Studio

  Transact-SQL

Before You Begin

Security

Permissions

Requires ALTER permission on the table.

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Using SQL Server Management Studio

To modify a unique constraint

1. In the Object Explorer, right-click the table containing the unique constraint and select Design.

2. On the Table Designer menu, click Indexes/Keys….

3. In the Indexes/Keys dialog box, under Selected Primary/Unique Key or Index, select the constraint you wish to edit.

4. Complete an action from the following table:

   To	Follow these steps
   Change the columns that the constraint is associated with	In the grid under (General), click Columns and then click the ellipses (…) to the right of the property. In the Index Columns dialog box, specify the new column or sort order or both for the index.
   Rename the constraint	In the grid under Identity, type a new name in the Name box. Make sure that your new name does not duplicate a name in the Selected Primary/Unique Key or Index list.
   Set the clustered option	In the grid under Table Designer, select Create As Clustered and from the dropdown choose Yes to create a clustered index and No to create a non-clustered one. Only one clustered index can exist per table. If a clustered index already exists in this table, you must clear this setting on the original index.
   Define a fill factor	In the grid under Table Designer, expand the Fill Specification category and type an integer from 0 to 100 in the Fill Factor box.

5. On the File menu, click Save table name.

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To modify a unique constraint

To modify a UNIQUE constraint using Transact-SQL, you must first delete the existing UNIQUE constraint and then re-create it with the new definition. For more information, see Delete Unique Constraints and Create Unique Constraints.

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