having limit in SQL queries on primary keys

Question

Hello,

I have table like;

CREATE TABLE IF NOT EXISTS `user_t` (
  `user_id` int(11) NOT NULL auto_increment,
  `name` varchar(20) NOT NULL,
  PRIMARY KEY  (`user_id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;

And lets say there is 1000 records in it.

Now I want to make a query where the user_id = 500.

Is it a good practice to user LIMIT 1 at the end of my query, as I know that my query is going to return only 1 row?

in fact is there a need for LIMIT at all as I am doing a query on a primary key, which is unique?

Answer 1

Using a limit when searching on a unique value is pointless. Either one record will be returned, or no records will be returned.

Answer 2

It's unnecessary to use LIMIT when querying with the primary key.

Answer 3

There is no need to use LIMIT 1 or TOP 1. Furthermore, it will likely confuse any developers that see it.

You will never get more than one row returned when querying against a single table using its primary key in the WHERE clause.