How to Efficiently Perform Bulk Deletion in SQL Server 2008?

Bulk Deletion in SQL Server 2008: An Exploration

The concept of bulk deletion arises when one seeks to delete a large number of rows from a table efficiently. While SQL Server's TRUNCATE command offers a rapid way to remove all rows from a table, it cannot accommodate WHERE clauses to selectively delete data.

Is Bulk Copying Applicable to Deletion?

Unfortunately, there is no direct equivalent to Bulk Copy (bcp) for deletion in SQL Server 2008. However, we can leverage alternative approaches to achieve bulk deletion.

Batch Deleting

Batch deleting involves splitting the deletion operation into smaller batches. This can be achieved using the following syntax:

SELECT 'Starting' --sets @@ROWCOUNT
WHILE @@ROWCOUNT <> 0
    DELETE TOP (xxx) MyTable WHERE ...

The 'Starting' statement sets the @@ROWCOUNT variable, which determines the number of rows to be deleted in each batch. The WHILE loop continues until all rows are deleted.

Using a Holding Table

If a substantial proportion of rows needs to be removed, a holding table can be used. The following steps outline this approach:

1. Create a holding table with the required columns.
2. Select rows to be kept in the holding table, excluding the ones to be deleted.
3. Truncate the original table to remove all rows.
4. Insert the rows from the holding table into the original table.

Conclusion

While there is no direct substitute for bulk copy for deletion in SQL Server 2008, the techniques discussed above provide viable alternatives. Batch deleting is suitable for selective deletion of smaller numbers of rows, while the holding table approach is beneficial for larger-scale deletions.

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