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法律學習我們如何透過從基礎表中選擇一定範圍的資料來建立一個 MySQL 檢視？
眾所周知，MySQL BETWEEN 運算子可用於從某些取值範圍內選擇值。我們可以將 BETWEEN 運算子與檢視結合起來，從基礎表中選擇某個取值範圍。為了理解該概念，我們使用包含以下資料的基礎表“student_info”——
mysql> Select * from Student_info; +------+---------+------------+------------+ | id | Name | Address | Subject | +------+---------+------------+------------+ | 101 | YashPal | Amritsar | History | | 105 | Gaurav | Chandigarh | Literature | | 125 | Raman | Shimla | Computers | | 130 | Ram | Jhansi | Computers | | 132 | Shyam | Chandigarh | Economics | | 133 | Mohan | Delhi | Computers | +------+---------+------------+------------+ 6 rows in set (0.00 sec)
示例
以下查詢將透過使用“BETWEEN”運算子建立一個名為“Info”的檢視，在特定範圍內選擇某些值——
mysql> Create or Replace view Info AS SELECT * from student_info WHERE Name BETWEEN 'C' AND 'P'; Query OK, 0 rows affected (0.14 sec) mysql> Select * from info; +------+--------+------------+------------+ | id | Name | Address | Subject | +------+--------+------------+------------+ | 105 | Gaurav | Chandigarh | Literature | | 133 | Mohan | Delhi | Computers | +------+--------+------------+------------+ 2 rows in set (0.00 sec)
同樣，我們可以將 BETWEEN 運算子與 NOT 結合使用，來選擇與我們在查詢中編寫的不同的取值範圍——
mysql> Create or Replace view Info AS SELECT * from student_info WHERE Name NOT BETWEEN 'C' AND 'P'; Query OK, 0 rows affected (0.06 sec) mysql> Select * from Info; +------+---------+------------+-----------+ | id | Name | Address | Subject | +------+---------+------------+-----------+ | 101 | YashPal | Amritsar | History | | 125 | Raman | Shimla | Computers | | 130 | Ram | Jhansi | Computers | | 132 | Shyam | Chandigarh | Economics | +------+---------+------------+-----------+ 4 rows in set (0.00 sec)
更新於:2020-6-22
133 次瀏覽
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