如何模擬 MySQL INTERSECT 查詢?
由於我們在 MySQL 中無法使用 INTERSECT 查詢,我們將使用 IN 運算子來模擬 INTERSECT 查詢。透過以下示例可以理解此過程 −
示例
在此示例中,我們有兩個表,分別是 Student_detail 和 Student_info,其中包含以下資料 −
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 IN 運算子的查詢將模擬 INTERSECT 查詢,以便返回同時存在於兩張表中的所有“studentid”值 −
mysql> Select Student_detail.studentid FROM Student_detail WHERE student_detail.studentid IN(SELECT Student_info.studentid FROM Student_info); +-----------+ | studentid | +-----------+ | 101 | | 105 | | 130 | | 132 | | 133 | +-----------+ 5 rows in set (0.06 sec)
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