MySQL 如何通过从基本表中选择一些值的范围来创建MySQL视图?
正如我们所知道的,MySQL BETWEEN操作符可以用于从一些值的范围中选择值。我们可以使用BETWEEN操作符来选择基本表中的一些值,以及视图。为了理解这个概念,我们使用具有以下数据的基本表“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)
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示例
以下查询将创建一个名为“Info”的视图,通过使用“BETWEEN”操作符选择特定范围内的一些值 –
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)
类似地,我们可以在BETWEEN操作符中使用NOT来选择不同于查询中写入的值的不同范围 –
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)