MySQL 如何创建一个空视图

MySQL 如何创建一个空视图

要在MySQL中创建一个空视图,请以下面的语法为准-

create or replace view yourViewName as
select yourValue AS yourColumnName,
yourValue AS yourColumnName2,
.
.
N
from dual
where false;
Mysql

实现上述语法以创建MySQL中的空视图 –

mysql> create or replace view empty_view as
   select "John Smith" AS ClientName,
   "US" AS ClientCountryName,
   false AS isMarried
   from dual
   where false;
Query OK, 0 rows affected (0.20 sec)
Mysql

检查视图描述 –

mysql> desc empty_view;
Mysql

将产生以下输出 –

+-------------------+-------------+------+-----+---------+-------+
| Field             | Type        | Null | Key | Default | Extra |
+-------------------+-------------+------+-----+---------+-------+
| ClientName        | varchar(10) | NO   |     |         |       |
| ClientCountryName | varchar(2)  | NO   |     |         |       |
| isMarried         | int(1)      | NO   |     | 0       |       |
+-------------------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)
Mysql

检查视图是否为空 –

mysql> select *from empty_view;
Empty set (0.00 sec)
Mysql

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