Which MySQL JOIN query is more efficient?

Question

Given the following table structure:

CREATE TABLE user (
   uid INT(11) auto_increment,
   name VARCHAR(200),
   PRIMARY KEY(uid)
);
CREATE TABLE user_profile(
          


        

Answer 1

The answer usually depends on the statistics gathered by database. The first form seems to be easier for optimizer.

As far as I remember, MySQL doesn't work well with IN... queries and subselects