ランダムな整数を取得する

 SET @nummin:=1;
 SET @nummax:=999999999999999999;

 SELECT
     LPAD(
         FLOOR( @nummin + (RAND() * (1 + @nummax)) )
        ,CHAR_LENGTH( CAST( @nummax AS CHAR ) )
        ,'0'
    ) AS rand_num
;