How to delete duplicate records from a table in MYSQL ?

Table Name : records

Procedure 1 :
Step 1 :

Create new table by removing duplicates

CREATE TABLE uniquerecords AS SELECT * FROM records GROUP BY name HAVING ( COUNT(name)>0 )

Step 2 :

Delete old table

DROP TABLE records

Step 3 :

Rename the New Table to Old Table

RENAME TABLE uniquerecords TO records

Procedure 2 : (IF Ajay is repeated five times, the below query would delete Ajay four times.)
QUERY :
DELETE FROM records USING records, records AS virtualtable WHERE (records.sno>virtualtable.sno) AND (records.name=virtualtable.name)
This would delete all the records except the first one.

Procedure 3 : (IF Ajay is repeated five times, the below query would delete all the five records.)
QUERY :
DELETE FROM records USING records, records AS virtualtable WHERE (records.sno=virtualtable.sno) AND (records.name=virtualtable.name)

How to get first 5 records from a table without using LIMIT in MYSQL ?

Table Name: records

Here, we have 10 records in the table, however, we need to retreive 5 records without using LIMIT keyword.

Query :

 SELECT limitrecordsone.sno,limitrecordsone.name FROM records limitrecordsone WHERE (SELECT COUNT(*) FROM records limitrecordstwo WHERE limitrecordstwo.sno <= limitrecordsone.sno) <=5

OUTPUT:

Get Player Name and Coach Name from a single table in MYSQL ?

Table Name: playercoach

Here, the number in the column coach represents the sno of the coach.

Procedure 1:

SELECT player.sno,player.name,(SELECT coach.name FROM playercoach coach WHERE coach.sno=player.coach) AS coachname FROM playercoach player

Procedure 2:

SELECT player.sno,player.name,coach.name AS coachname FROM playercoach player JOIN playercoach coach ON coach.sno=player.coach

Output:

Procedure 1 would be better in the sense of performance.