可以将MariaDB或MySQL转换为bigint,收到错误：…在’bigint’附近使用正确的语法’？

如果我想要一个字符串并创建一个表(这在strict mode中失败),

CREATE TABLE g
  AS SELECT CAST('2147483699' AS int);

我如何告诉它我想要一个bigint类型？我也会得到一个int(10)类型.选择它也很幽默,

+---------------------------+
| CAST('2147483699' AS int) |
+---------------------------+
|                2147483647 |
+---------------------------+

数据实际上是错误的,它默默地失败了. I know that’s a known issue with this database having really poor defaults,但我怎么能把这张桌子作为bigint创建呢？

CREATE TABLE g
  AS SELECT CAST('2147483699' AS bigint);

这样做我得到这个错误,

ERROR 1064 (42000): You have an error in your sql Syntax; check the manual that corresponds to your MariaDB server version for the right Syntax to use near ‘bigint)’ at line 2

如何将一个整数投入bigint？

Postgresql的

使用Postgresql,它非常简单.除了在转换为int时抛出异常,还可以使用强制转换为bigint

SELECT CAST('2147483699' AS bigint);
    int8    
------------
 2147483699

解决方法:

默默？我们试试吧：

CREATE TABLE g
   AS SELECT CAST('2147483699' AS int);

MariaDB 10.1.32,默认sql_mode(非严格)

Query OK, 1 row affected, 1 warning (0.19 sec) Records: 1 Duplicates:
0 Warnings: 1

警告是：

| Warning | 1264 | Out of range value for column ‘CAST(‘2147483699′ AS int)’ at row 1 |

是的,从表格中选择是有趣的,但鉴于警告,这并不奇怪.

(我目前没有MariaDB 10.2实例,但是对dbfiddle.uk进行测试表明它也失败了,尽管再次没有静默.)

MariaDB 10.3.6,默认sql_mode(严格)

没有警告.

select * from g;

得到：

+---------------------------+
| CAST('2147483699' AS int) |
+---------------------------+
|                2147483699 |
+---------------------------+
1 row in set (0.000 sec)

并且该列确实被创建为bigint(10).

MysqL 8.0,默认严格和非严格sql_mode

ERROR 1064 (42000): You have an error in your sql Syntax; check the manual that corresponds to your MysqL server version for the right Syntax to use near ‘int)’ at line 2

电脑说没有.

结论

MariaDB或MysqL可以作为bigint投射吗？正如我们所看到的,是的,MariaDB 10.3可以(虽然它还不是GA ……但现在肯定会是任何一天).但是,它只能隐式地转换为bigint.您不能显式地转换为bigint,就像您不能转换为varchar(但请参阅MDEV-11283),text,float,tinyint等.您可以强制转换为有限数量的数据类型.这没有很好的文档记录,但CAST似乎只支持与CONVERT function列出的相同数据类型.