範例 EXCEPT 查詢

TICKIT 資料庫中的 CATEGORY 資料表包含以下 11 個資料列：

 catid | catgroup |  catname  |                  catdesc
-------+----------+-----------+--------------------------------------------
   1   | Sports   | MLB       | Major League Baseball
   2   | Sports   | NHL       | National Hockey League
   3   | Sports   | NFL       | National Football League
   4   | Sports   | NBA       | National Basketball Association
   5   | Sports   | MLS       | Major League Soccer
   6   | Shows    | Musicals  | Musical theatre
   7   | Shows    | Plays     | All non-musical theatre
   8   | Shows    | Opera     | All opera and light opera
   9   | Concerts | Pop       | All rock and pop music concerts
  10   | Concerts | Jazz      | All jazz singers and bands
  11   | Concerts | Classical | All symphony, concerto, and choir concerts
(11 rows)

假設 CATEGORY_STAGE 資料表 (臨時資料表) 包含一個額外的資料列：

 catid | catgroup |  catname  |                  catdesc
-------+----------+-----------+--------------------------------------------
1 | Sports   | MLB       | Major League Baseball
2 | Sports   | NHL       | National Hockey League
3 | Sports   | NFL       | National Football League
4 | Sports   | NBA       | National Basketball Association
5 | Sports   | MLS       | Major League Soccer
6 | Shows    | Musicals  | Musical theatre
7 | Shows    | Plays     | All non-musical theatre
8 | Shows    | Opera     | All opera and light opera
9 | Concerts | Pop       | All rock and pop music concerts
10 | Concerts | Jazz      | All jazz singers and bands
11 | Concerts | Classical | All symphony, concerto, and choir concerts
12 | Concerts | Comedy    | All stand up comedy performances
(12 rows)

傳回兩個資料表之間的差異。換句話說，會傳回 CATEGORY_STAGE 資料表而非 CATEGORY 資料表中的資料列：

select * from category_stage
except
select * from category;

catid | catgroup | catname |             catdesc
-------+----------+---------+----------------------------------
12 | Concerts | Comedy  | All stand up comedy performances
(1 row)

以下對等查詢使用同義詞 MINUS。

select * from category_stage
minus
select * from category;

catid | catgroup | catname |             catdesc
-------+----------+---------+----------------------------------
12 | Concerts | Comedy  | All stand up comedy performances
(1 row)

若您將 SELECT 表達式的順序反轉，則查詢不會傳回任何資料列。