is it necessary to use LIMIT 1?

[cssExp]

Hi,

Suppose I have the following query:

SELECT * FROM `users` WHERE `user_name`='somename'

here the `user_name` field is primary key as well.

In the above, the user somename is retrieved through php. Anyway, my question is, if I know that there will only be one user of the same name - is it requrred to use LIMIT 1?

SELECT * FROM `users` WHERE `user_name`='somename' LIMIT 1

My brother says it's more efficient to do so, but I read somewhere that it may slow things down. But since it's just LIMIT 1 there shouldn't be much issue with speed. But I want to know what's the best practice.

Thanks

[r937]

LIMIT 1 is ~not~ required if your WHERE clause guarantees only one row

best practice would be to leave it out

LIMIT is mysql syntax, and will not work if you ever have to port your code to a different database