gistfile1.txt

Using this Table definition...

CREATE TABLE test (
	id     	INT NOT NULL,
	last_name  CHAR(30) NOT NULL,
	first_name CHAR(30) NOT NULL,
	PRIMARY KEY (id),
	INDEX name (first_name, last_name)
);

Which query is faster for selecting a user's first name?
SELECT * FROM test WHERE first_name = 'john' AND last_name = 'smith'
SELECT first_name FROM test WHERE last_name = 'smith' AND first_name = 'john'

Is one query more efficient than the other?
SELECT * FROM test WHERE last_name = 'smith' AND first_name = 'john'
SELECT * FROM test WHERE first_name = 'john' AND last_name = 'smith'

Will this query use the "name" index?
SELECT * FROM test WHERE last_name = 'smith'