[SOLVED] SQL Group problem

SQL Group problem

I have this query which is showing the ORA-00979:not a GROUP BY expression error.

I'm not a sql pro so please could you give me a hint what's wrong ?

SELECT *
  FROM (SELECT a.*, ROWNUM r___
          FROM (SELECT DISTINCT "SMTAPP"."XF_MASTER"."ID" AS "XfMasterEntityId",
                                "SMTAPP"."XP_MASTER_DETAIL"."WIFENAME" AS "XpMasterDetailEntityWifename",
                                "SMTAPP"."XP_MASTER_DETAIL"."COUNT" AS "XpMasterDetailEntityCount",
                                MAX ("SMTAPP"."XP_MASTER_DETAIL"."COUNT") AS "XpMasterDetailEntityCountMax"
                           FROM ("SMTAPP"."XF_MASTER" LEFT JOIN "SMTAPP"."XP_MASTER_DETAIL"
                                ON "SMTAPP"."XF_MASTER"."ID" =  "SMTAPP"."XP_MASTER_DETAIL"."XF_MASTER_ID")
                       GROUP BY "SMTAPP"."XP_MASTER_DETAIL"."COUNT"
                       ORDER BY "SMTAPP"."XF_MASTER"."ID" ASC) a
         WHERE ROWNUM < '11')
 WHERE r___ >= '1'

Solution

Try to add other columns from SELECT into GROUP BY: ID and WIFENAME