Question

I need to update a lot of rows, per a user request. It is a site with products.

I could…

• Delete all old rows for that product, then loop through string building a new INSERT query. This however will lose all data if the INSERT fails.
• Perform an UPDATE through each loop. This loop currently iterates over 8 items, but in the future it may get up to 15. This many UPDATEs doesn’t sound like too good an idea.
• Change DB Schema, and add an auto_increment Id to the rows. Then first do a SELECT, get all old rows ids in a variable, perform one INSERT, and then a DELETE WHERE IN SET.

What is the usual practice here?

Thanks

Answer 1

Just do the updates. In a transaction if you need to. 15 updates is peanuts, unless you’re doing it on every page access or something.

You don’t want to be deleting/re-inserting rows just to avoid extra queries. And you won’t be able to, if you ever want to have a foreign key referencing the table you’re updating.

Almost certainly a premature optimisation.