As a SQL Server user, you may have come across the question of whether it is possible to delete or update multiple tables in a single statement. This is a common query that many users have, and it is important to understand the limitations and best practices when it comes to manipulating data in SQL Server.

The answer to the question is both simple and complex. The simple answer is that SQL Server does not support deleting or updating from two tables in a single update statement. This means that if you want to delete or update data in multiple tables, you will need to write separate delete or update statements for each table.

There are several reasons why SQL Server does not allow deleting or updating from multiple tables in a single statement. One of the main reasons is data consistency. When you perform a delete or update operation, SQL Server needs to ensure that the changes are applied correctly and that the data remains consistent across all related tables. Performing these operations in a single statement can lead to data integrity issues and inconsistencies.

Another reason is SQL syntax. SQL Server follows ANSI Entry SQL standards for referential integrity between primary key and foreign key columns. This means that the inserting, updating, and deleting of data in related tables should be restricted to values that preserve the integrity. Writing a single statement to delete or update multiple tables goes against these standards and can result in syntax errors.

It is important to note that there is a concept called cascading delete or cascading update in SQL Server. This concept is used to maintain data integrity by automatically deleting or updating related records when a primary key is deleted or updated. However, this is a different concept from deleting or updating multiple tables in a single statement.

When someone asks about deleting or updating multiple tables in a single statement, they are usually referring to a syntax like this:

DELETE/UPDATE Table1 (cols), Table2 (cols)
VALUES ...

This syntax is not valid and does not follow ANSI standards. It is important to understand the difference between cascading delete or update and deleting or updating multiple tables in a single statement.

In conclusion, while it may seem convenient to delete or update multiple tables in a single statement, it is not supported by SQL Server and should not be implemented. It is important to follow best practices and write separate delete or update statements for each table to ensure data consistency and adhere to SQL syntax standards.

Thank you for reading this blog post. If you have any further questions or would like to learn more about SQL Server concepts, feel free to leave a comment below.