best way for select row mysql

Question

Which of the following notations is better?

SELECT id,name,data FROM table WHERE id = X

OR

SELECT id,name,data FROM table WHERE id = X LIMIT 1

I think it should not have "LIMIT".

Thanks!

Answer 1

If there is a unique constraint on id then they will be exactly the same.

If there isn't a unique constraint (which I would find highly surprising on a column called id) then which is better depends on what you want to do:

• If you want to find all rows matching the condition, don't use LIMIT.
• If you want to find any row matching the condition (and you don't care which), use LIMIT 1.

Answer 2

Always use LIMIT with select statement even if you are fetching 1 record because it will speed up your query. So use :

SELECT id,name,data FROM table WHERE id = X LIMIT 1

For example : If there are 1000 records in your table than if you using

SELECT id,name,data FROM table WHERE id = X

than it will traverse through 1000 records even if finds that id But if you using LIMIT like this

SELECT id,name,data FROM table WHERE id = X LIMIT 1

than it will stop executing when finds first record.