我们如何通过从基础表中选择一定范围的数据来创建一个 MySQL 视图？

众所周知，MySQL BETWEEN 运算符可用于从某些取值范围内选择值。我们可以将 BETWEEN 运算符与视图结合起来，从基础表中选择某个取值范围。为了理解该概念，我们使用包含以下数据的基础表“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

以下查询将通过使用“BETWEEN”运算符创建一个名为“Info”的视图，在特定范围内选择某些值——

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)

同样，我们可以将 BETWEEN 运算符与 NOT 结合使用，来选择与我们在查询中编写的不同的取值范围——

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)

更新于:2020-6-22

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