SET @newid=0;
UPDATE tablename SET primary_key_id=(@newid:=@newid+1) ORDER BY primary_key_id;
This query will reindex the primary key starts from 1
SET @newid=0;
UPDATE tablename SET primary_key_id=(@newid:=@newid+1) ORDER BY primary_key_id;
This query will reindex the primary key starts from 1