Question

美好的一天！
我有一个表T1（在MariaDB）与二进制列C1。它有一些字节。

当我选择HEX时，我有以下内容：

select HEX(SUBSTRING((select C1 from T1 where <some restrictions>), 254, 2));
+----------------------------------------------------------------------+
| HEX(SUBSTRING((select C1 from T1 where <some restrictions>), 254, 2)) |
+----------------------------------------------------------------------+
| 1200                                                                 |
+----------------------------------------------------------------------+

但我未能将结果转换为INT：

select cast((SUBSTRING((select C1 from T1 where <some restrictions>), 254, 2)) as int);
+--------------------------------------------------------------------------------+
| cast((SUBSTRING((select C1 from T1 where <some restrictions>), 254, 2)) as int) |
+--------------------------------------------------------------------------------+
|                                                                              0 |
+--------------------------------------------------------------------------------+

所以，我的问题是 - 为什么会发生这种情况，如何将二进制转换为int？

Answer 1

类型有：无符号整数或有符号整数

select cast((substring((select C1 from T1 where <some restrictions>), 254, 2)) as unsigned integer);

select cast(substring( '12345', 1, 2 ) as unsigned integer)

MariaDB将二进制转换为int

1 个答案: