해커랭크(HackerRank) SQL 문제풀이 - Print Prime Numbers

SELECT GROUP_CONCAT(NU1 SEPARATOR '&')
    FROM(SELECT @NUM:=@NUM+1 AS NU1
            FROM informAtion_schema.tables T1,
                informAtion_schema.tables T2,(SELECT @NUM:=1) TMP
        ) TEMPNUM1
    WHERE NU1<=1000
    AND NOT EXISTS (SELECT *
                    FROM (SELECT @NUMB:=@NUMB+1 AS NU2
                        FROM informAtion_schema.tables T1,
                            informAtion_schema.tables T2,
                            (SELECT @NUMB:=1) TMP2
                        LIMIT 1000) TEMPNUM2
                    WHERE FLOOR(NU1/NU2)=(NU1/NU2)
                    AND NU2<NU1 AND 1<NU2)