示例摘自：極客代碼：http://wiki.jikexueyuan.com/project/sql/useful-functions/except-clause.html
EXCEPT 子句
EXCEPT 子句/運算符用於將兩個 SELECT 語句結合在一起，並返回第一個 SELECT 語句的結果中那些不存在於第二個 SELECT 語句結果的記錄。這就意味着，EXCEPT 僅返回那些不存在於第二個 SELECT 語句結果的記錄（差集）。
EXCEPT 運算符遵循同 UNION 運算符一樣的規則。MySQL 不支持 EXCEPT 運算符。
EXCEPT子句的基本語法如下所示：
SELECT column1 [, column2 ]
FROM table1 [, table2 ]
[WHERE condition]
EXCEPT
SELECT column1 [, column2 ]
FROM table1 [, table2 ]
[WHERE condition]這里給定的條件可以是任何根據你自己的需要而得出的表達式。
示例：
考慮如下兩個表格，（a）CUSTOMERS 表：
+----+----------+-----+-----------+----------+
| ID | NAME | AGE | ADDRESS | SALARY |
+----+----------+-----+-----------+----------+
| 1 | Ramesh | 32 | Ahmedabad | 2000.00 |
| 2 | Khilan | 25 | Delhi | 1500.00 |
| 3 | kaushik | 23 | Kota | 2000.00 |
| 4 | Chaitali | 25 | Mumbai | 6500.00 |
| 5 | Hardik | 27 | Bhopal | 8500.00 |
| 6 | Komal | 22 | MP | 4500.00 |
| 7 | Muffy | 24 | Indore | 10000.00 |
+----+----------+-----+-----------+----------+（b）ORDERS 表：
+-----+---------------------+-------------+--------+
| OID | DATE | ID | AMOUNT |
+-----+---------------------+-------------+--------+
| 102 | 2009-10-08 00:00:00 | 3 | 3000 |
| 100 | 2009-10-08 00:00:00 | 3 | 1500 |
| 101 | 2009-11-20 00:00:00 | 2 | 1560 |
| 103 | 2008-05-20 00:00:00 | 4 | 2060 |
+-----+---------------------+-------------+--------+現在，讓我將這兩個表的 EXCEPT 查詢的結果結合在一起：
SQL> SELECT ID, NAME, AMOUNT, DATE
FROM CUSTOMERS
LEFT JOIN ORDERS
ON CUSTOMERS.ID = ORDERS.CUSTOMER_ID
EXCEPT
SELECT ID, NAME, AMOUNT, DATE
FROM CUSTOMERS
RIGHT JOIN ORDERS
ON CUSTOMERS.ID = ORDERS.CUSTOMER_ID;其結果如下所示：
+----+---------+--------+---------------------+ | ID | NAME | AMOUNT | DATE | +----+---------+--------+---------------------+ | 1 | Ramesh | NULL | NULL | | 5 | Hardik | NULL | NULL | | 6 | Komal | NULL | NULL | | 7 | Muffy | NULL | NULL | +----+---------+--------+---------------------+
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 分割線 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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-- 測試表，與測試數據
);
);
INSERT INTO union_tab_1 VALUES(2, 'B');
INSERT INTO union_tab_1 VALUES(3, 'C');
INSERT INTO union_tab_2 VALUES(1, 'A');
INSERT INTO union_tab_2 VALUES(1, 'A');
INSERT INTO union_tab_2 VALUES(2, 'B');
INSERT INTO union_tab_2 VALUES(4, 'D');
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EXCEPT– 返回第一個表中有、第二個表中沒有的數據
SQL Server 支持
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MySQL 不支持
實現相同功能的 SQL 如下：
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