Microsoft sql purge

The example removes the Sales and NewSales databases. Back up the master database. If master must be restored, any database that has been deleted since the last backup of master will still have references in the system catalog views and may cause error messages to be raised. Skip to main content. This browser is no longer supported. Download Microsoft Edge More info.

Contents Exit focus mode. The cursor variable must reference a cursor that allows updates. CATCH construct. If the DELETE removes multiple rows, and any one of the removed rows violates a trigger or constraint, the statement is canceled, an error is returned, and no rows are removed.

The rest of the batch is canceled, and an error message is returned. DELETE can be used in the body of a user-defined function if the object modified is a table variable. See the Examples section that follows in this topic. By default, a DELETE statement always acquires an intent exclusive IX lock on the table object and pages it modifies, an exclusive X lock on the rows it modifies, and holds those locks until the transaction completes.

With an intent exclusive IX lock, no other transactions can modify the same set of data; read operations can take place only with the use of the NOLOCK hint or read uncommitted isolation level. You can specify table hints to override this default behavior for the duration of the DELETE statement by specifying another locking method, however, we recommend that hints be used only as a last resort by experienced developers and database administrators.

When rows are deleted from a heap the Database Engine may use row or page locking for the operation. As a result, the pages made empty by the delete operation remain allocated to the heap.

When empty pages are not deallocated, the associated space cannot be reused by other objects in the database. This allows the pages to be deallocated. Create a clustered index on the heap before deleting the rows. You can drop the clustered index after the rows are deleted. This method is more time consuming than the previous methods and uses more temporary resources.

Examples in this section demonstrate the basic functionality of the DELETE statement using the minimum required syntax. The following example executes core. Therefore, the default value of NULL is used for all parameters, with the associated behavior.

The following example removes data from the management data warehouse that is older than 7 days. In addition, the duration parameter is specified so that the operation will run no longer than 5 minutes. The following example removes data from the management data warehouse for a given collection set on the specified instance of SQL Server.

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