til/mysql/run-statements-in-a-transaction.md

Run Statements In A Transaction

I'm connecting to a production MySQL database to make some changes to a specific user account. That means I am going to run an update statement and I expect that statement to affect exactly one row in the users table.

If I run the update statement in a transaction, then I can verify all looks good before committing those changes. And importantly, I can rollback the changes if anything looks off.

> start transaction;

> update users set roles = 'admin' where id = '1234';
Query ok, 1 row affected

> select * from users where id = '1234';
-- check that all looks good

> commit;

In the above case, all looked good, so I ran commit. If more rows than I expected were affected or the changed record didn't look right, I could instead rollback. None of those changes would make it into live production data.

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