Table Name: playercoach
Here, the number in the column coach represents the sno of the coach.
SELECT player.sno,player.name,(SELECT coach.name FROM playercoach coach WHERE coach.sno=player.coach) AS coachname FROM playercoach player
SELECT player.sno,player.name,coach.name AS coachname FROM playercoach player JOIN playercoach coach ON coach.sno=player.coach
Procedure 1 would be better in the sense of performance.