Question

I am using MySQL as database. I need to update some data. However the data may haven’t changed so I may not need to update the row in such case.

I wanted to know which one will be better (performance wise):

a) Search the table to determine if the data has changed. For example I can search by primary key and then see if the value of remaining fields have changed or not. If yes, then continue with update statement and if not then leave it.

b) Use UPDATE query directly. If there are no changes in the data, MySQL will automatically ignore it and not process updating the data.

So which one will be perform better in such case.

Answer 1

From the MySQL manual:

If you set a column to the value it currently has, MySQL notices this
and does not update it.

So save yourself the latency and leave that task to MySQL. It will even tell you how many rows were actually affected.