由於我們無法在 MySQL 中使用 MINUS 查詢，因此我們將使用 LEFT JOIN 來模擬 MINUS 查詢。可以藉助以下範例來理解：
在此範例中，我們有兩個表，即Student_detail 和Student_info，其內容如下資料-
mysql> Select * from Student_detail; +-----------+---------+------------+------------+ | studentid | Name | Address | Subject | +-----------+---------+------------+------------+ | 101 | YashPal | Amritsar | History | | 105 | Gaurav | Chandigarh | Literature | | 130 | Ram | Jhansi | Computers | | 132 | Shyam | Chandigarh | Economics | | 133 | Mohan | Delhi | Computers | | 150 | Rajesh | Jaipur | Yoga | | 160 | Pradeep | Kochi | Hindi | +-----------+---------+------------+------------+ 7 rows in set (0.00 sec) mysql> Select * from Student_info; +-----------+-----------+------------+-------------+ | studentid | Name | Address | Subject | +-----------+-----------+------------+-------------+ | 101 | YashPal | Amritsar | History | | 105 | Gaurav | Chandigarh | Literature | | 130 | Ram | Jhansi | Computers | | 132 | Shyam | Chandigarh | Economics | | 133 | Mohan | Delhi | Computers | | 165 | Abhimanyu | Calcutta | Electronics | +-----------+-----------+------------+-------------+ 6 rows in set (0.00 sec)
現在，以下使用LEFT JOIN 的查詢將模擬MINUS 以傳回Student_info 中的「studentid」值，但不傳回Student_detail 表中的值。
mysql> SELECT studentid from student_info LEFT JOIN Student_detail USING(studentid) WHERE student_detail.studentid IS NULL; +-----------+ | studentid | +-----------+ | 165 | +-----------+ 1 row in set (0.07 sec)
現在，以下查詢將為我們提供與上述查詢相反的結果，即它將傳回 Student_detail 中的「studentid」值，但不會傳回 Student_info 表中的值。
mysql> SELECT studentid from student_detail LEFT JOIN Student_info USING(studentid) WHERE student_info.studentid IS NULL; +-----------+ | studentid | +-----------+ | 150 | | 160 | +-----------+ 2 rows in set (0.00 sec)
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