Delete primary keys

Applies to: SQL Server 2016 (13.x) and later versions Azure SQL Database Azure SQL Managed Instance SQL database in Microsoft Fabric

You can delete (drop) a primary key in SQL Server by using SQL Server Management Studio or Transact-SQL.

When the primary key is deleted, the corresponding index is deleted. This index might be the clustered index of the table, causing the table to become a heap. For more information, see Heaps (tables without clustered indexes). Most tables should have a clustered index. To re-create the primary key, see Create primary keys.

Primary keys can be referenced by foreign keys in another table. If referenced by a foreign key, you need to drop referencing foreign keys first, then drop the primary key. For more information, see Primary and foreign key constraints.

Permissions

Requires ALTER permission on the table.

Use SQL Server Management Studio

Delete a primary key constraint using Object Explorer

1. In Object Explorer, expand the table that contains the primary key and then expand Keys.

2. Right-click the key and select Delete.

3. In the Delete Object dialog box, verify the correct key is specified and select OK.

Delete a primary key constraint using Table Designer

1. In Object Explorer, right-click the table with the primary key, and select Design.

2. In the table grid, right-click the row with the primary key and choose Remove Primary Key to toggle the setting from on to off.

   Note

   To undo this action, close the table without saving the changes. Deleting a primary key can't be undone without losing all other changes made to the table.

3. On the File menu, select Save table name.

Use Transact-SQL

Delete a primary key constraint

1. In Object Explorer, connect to an instance of Database Engine.

2. On the Standard bar, select New Query.

3. Copy and paste the following example into the query window and select Execute.

   • You must first identify the name of the primary key constraint.

     SQL

     USE AdventureWorks2022;
     GO
     
     -- Return the name of primary key.
     SELECT name
     FROM sys.key_constraints
     WHERE type = 'PK'
         AND OBJECT_NAME(parent_object_id) = N'TransactionHistoryArchive';
     GO
     

   • To create the DROP script, use the result from the previous query. Replace <primary-key-constraint> with the correct value. It might look similar to PK_TransactionHistoryArchive_TransactionID.

     SQL

     ALTER TABLE Production.TransactionHistoryArchive
         DROP CONSTRAINT <primary-key-constraint>;
     GO
     

Related content

• ALTER TABLE (Transact-SQL)
• sys.key_constraints (Transact-SQL)
• Clustered and nonclustered indexes