子查询

以下示例在WHERE子句中包含一个表子查询，该子查询生成多个行。在本示例中，行只包含一列，但表子查询可以包含多个列和行，就像任何其他表一样。

以下查询查找门票销量排名前10位的卖家。

select firstname, lastname, cityname, max(qtysold) as maxsold
from users join sales on users.userid=sales.sellerid
where users.city not in(select venuecity from venue)
group by firstname, lastname, city
order by maxsold desc, city desc
limit 10;
firstname  | lastname |      cityname  | maxsold
-----------+----------+----------------+---------
Noah       | Guerrero | Worcester      |       8
Isadora    | Moss     | Winooski       |       8
Kieran     | Harrison | Westminster    |       8
Heidi      | Davis    | Warwick        |       8
Sara       | Anthony  | Waco           |       8
Bree       | Buck     | Valdez         |       8
Evangeline | Sampson  | Trenton        |       8
Kendall    | Keith    | Stillwater     |       8
Bertha     | Bishop   | Stevens Point  |       8
Patricia   | Anderson | South Portland |       8
(10 rows)