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)
mysql> Select * from Student_detail;
+-----------+-------------+------------+
| Studentid | StudentName | address |
+-----------+-------------+------------+
| 100 | Gaurav | Delhi |
| 101 | Raman | Shimla |
| 103 | Rahul | Jaipur |
| 104 | Ram | Chandigarh |
| 105 | Mohan | Chandigarh |
+-----------+-------------+------------+
5 rows in set (0.00 sec)
示例
下面的查询将使用上述两个表中的数据创建一个视图 -
mysql> Create or Replace View Info AS Select StudentName from Student_detail UNION Select Name From Student_info;
Query OK, 0 rows affected (0.10 sec)
mysql> select * from info;
+-------------+
| StudentName |
+-------------+
| Gaurav |
| Raman |
| Rahul |
| Ram |
| Mohan |
| YashPal |
| Shyam |
+-------------+
7 rows in set (0.00 sec)
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上面的结果集包含两列中的值的组合。如果一个值重复，那么它会消除重复的值。
我们还可以存储所有值，也可以通过使用 UNION ALL 来重复一个值，如以下查询所示 -
mysql> Create or Replace View Info AS Select student name from Student_detail UNION ALL Select Name From Student_info;
Query OK, 0 rows affected (0.16 sec)
mysql> select * from info;
+-------------+
| StudentName |
+-------------+
| Gaurav |
| Raman |
| Rahul |
| Ram |
| Mohan |
| YashPal |
| Gaurav |
| Raman |
| Ram |
| Shyam |
| Mohan |
+-------------+
11 rows in set (0.00 sec)
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