Question

I have a database which consist of 300 tables with data in it. I need to delete all the data inside each tables. I tried to truncate all tables but then I got an error that the process could not be completed because one of the column in a table is a foreign key. Is there other way to resolve my problem? Thanks.

Answer 1

You need to either:

• remove all the foreign keys, truncate, then re-create FKs;
• disable all the foreign keys, delete (not truncate), then re-enable FKs; or,
• delete from child tables first.

The latter may not be possible if you’re lucky enough to have circular references, and it can still be complicated even without circular references. The first two are also relatively complex, but I solved a very similar problem for a different user recently (and I find these easier than trying to determine the proper delete order):

Temporarily disable all foreign key constraints

Another idea is to perform a simpler and more complete wipe:

• script the tables (and other objects obviously), drop the database and re-create it; or,
• create a copy of the database, and use Visual Studio / SSDT or a 3rd party schema comparison tool to create all of the objects in the empty database (then you can drop the old database and rename the new one).