Postgres SQL：如何在此SQL中执行GROUP BY

Question

我们有下面的SQL，它从审核表family_audit和family_address_audit生成报告。

(SELECT fam.familyserialno, fam.familyname, addr.housenumber, addr.address1,
        COALESCE(fam.operation, addr.operation) op,
        COALESCE(fam.username, addr.username) usr,
        COALESCE(fam.adddate, addr.adddate) add_date,
        (SELECT r.userrolename 
           FROM userrole_master r, user_master u 
          WHERE u.loginid=COALESCE(fam.username, addr.username) AND r.userrole_id=u.userrole_id) rolename
  FROM family_audit fam
       INNER JOIN family_address_audit addr USING(txid, family_id)
WHERE (fam.node_id = 8) AND (fam.familyserialno >=1 and fam.familyserialno <=5)
)
UNION
(SELECT fam.familyserialno, fam.familyname,
        addr.housenumber, addr.address1,
        COALESCE(fam.operation, addr.operation) op,
        COALESCE(fam.username, addr.username) usr,
        COALESCE(fam.adddate, addr.adddate) add_date,
        (SELECT r.userrolename 
           FROM userrole_master r, user_master u 
          WHERE u.loginid=COALESCE(fam.username, addr.username) AND r.userrole_id=u.userrole_id) rolename
   FROM family_audit fam
        FULL OUTER JOIN family_address_audit addr USING(txid, family_id)
  WHERE ((fam.familyserialno IS NULL and addr.family_id in 
             (select family_id 
                from family 
               where familyserialno >=1 and familyserialno <=5 and node_id =8)) 
         OR ((addr.family_id IS NULL) and ((fam.familyserialno >=1 and fam.familyserialno <=5) and fam.node_id=8) ) )
)
ORDER BY add_date DESC;

来自“上方” SQL的典型输出如下所示

 familyserialno | familyname | housenumber |  address1  | op |  usr  |        add_date         | rolename
----------------+------------+-------------+------------+----+-------+-------------------------+----------
              3 | thirda     |             |            | U  | admin | 2010-11-24 15:29:34.312 | admin
                |            | 34324       | sdfdsfdsf  | U  | admin | 2010-11-24 15:28:42.314 | admin
              3 | third      |             |            | I  | admin | 2010-11-24 15:28:34.576 | admin
                |            | 333         | sdfdsf     | U  | admin | 2010-11-24 15:18:57.129 | admin
              2 | aSecond    |             |            | I  | admin | 2010-11-24 14:58:15.477 | admin
              1 | anjanFirst | anjanFirst  | anjanFirst | I  | admin | 2010-11-24 14:12:35.477 | admin

======================

我想按fam.familyserialno对输出进行分组。 因此，我修改了上面的SQL，如下所示： 但是，这会导致错误（最后）

SELECT * from 
((SELECT fam.familyserialno, fam.familyname, addr.housenumber, addr.address1,
        COALESCE(fam.operation, addr.operation) op,
        COALESCE(fam.username, addr.username) usr,
        COALESCE(fam.adddate, addr.adddate) add_date,
        (SELECT r.userrolename 
           FROM userrole_master r, user_master u 
          WHERE u.loginid=COALESCE(fam.username, addr.username) AND r.userrole_id=u.userrole_id) rolename
  FROM family_audit fam
       INNER JOIN family_address_audit addr USING(txid, family_id)
WHERE (fam.node_id = 8) AND (fam.familyserialno >=1 and fam.familyserialno <=5)
)
UNION
(SELECT fam.familyserialno, fam.familyname,
        addr.housenumber, addr.address1,
        COALESCE(fam.operation, addr.operation) op,
        COALESCE(fam.username, addr.username) usr,
        COALESCE(fam.adddate, addr.adddate) add_date,
        (SELECT r.userrolename 
           FROM userrole_master r, user_master u 
          WHERE u.loginid=COALESCE(fam.username, addr.username) AND r.userrole_id=u.userrole_id) rolename
   FROM family_audit fam
        FULL OUTER JOIN family_address_audit addr USING(txid, family_id)
  WHERE ((fam.familyserialno IS NULL and addr.family_id in 
             (select family_id 
                from family 
               where familyserialno >=1 and familyserialno <=5 and node_id =8)) 
         OR ((addr.family_id IS NULL) and ((fam.familyserialno >=1 and fam.familyserialno <=5) and fam.node_id=8) ) )
))
GROUP BY 1 
ORDER BY 7 DESC;

错误：FROM中的子查询必须具有别名第2行：（（（SELECT fam.familyserialno，fam.familyname，addr.housenumbe ... ^提示：例如，FROM（SELECT ...）[AS] foo。

我该如何解决 ？ 我们确实需要将所有行按fam.familyserialno分组。

非常感谢你，

PS：我们正在使用Postgres 8.4.4。

Answer 1

您需要为子查询添加别名，如下所示：

 SELECT * FROM ((SELECT ...) UNION (SELECT ...)) AS foo GROUP BY 1 ORDER BY 7 DESC;

foo是子查询的别名。