Question

使用Mysql的奇怪之处（5.6.39）我想在视图中创建一些varchar数据类型的文本。只是示例（如果我使用真实表中的实际数据，也会发生同样的事情）：

最长可达512

CREATE
algorithm = UNDEFINED
SQL SECURITY DEFINER
view conversiontest2(field1) as
select cast('sometext' as char(512) charset utf8);

结果：

MySQL [xx]> show columns from conversiontest2;
+--------+--------------+------+-----+---------+-------+
| Field  | Type         | Null | Key | Default | Extra |
+--------+--------------+------+-----+---------+-------+
| field1 | varchar(512) | NO   |     |         |       |
+--------+--------------+------+-----+---------+-------+

如果我使用任何大于512的值

> ALTER
-> algorithm = UNDEFINED
-> SQL SECURITY DEFINER
-> view conversiontest2(field1) as
-> select cast('sometext' as char(513) charset utf8)
-> ;
Query OK, 0 rows affected (0.00 sec)

MySQL [xx]> show columns from conversiontest2;
+--------+------+------+-----+---------+-------+
| Field  | Type | Null | Key | Default | Extra |
+--------+------+------+-----+---------+-------+
| field1 | text | NO   |     | NULL    |       |
+--------+------+------+-----+---------+-------+
1 row in set (0.00 sec)

我错过了什么？相同的结果（当然）使用convert（）而不是cast（）..

尽管使用强制转换/转换为char，Mysql视图列仍然保留文本

0 个答案: