Which is optimal query for check whether the username ans password present in MySql database.
1)SELECT * FROM login_details WHERE username='username' AND password='password'
2)SELECT count(*)FROM login_details WHERE username='username' AND password='password'
3)SELECT count(Username)FROM login_details WHERE username='username' AND password='password'
4)SELECT 1 FROM login_details WHERE username='username' AND password='password'
Thanks