如何对我的 varbinary 列中的第 N 个字节执行二进制操作？

Question

我已经能够使用 substring(colname, N, 1) 从字段中取出第 N 个字节，但此时似乎无法将结果视为二进制：

> select substring(colname, N, 1) from [...]
\
> select hex(substring(colname, N, 1)) from [...]
5C
> select hex(substring(colname, N, 1) & 0xff) from [...]
0
> select cast(substring(colname, N, 1) as unsigned integer) from [...]
0

相比于：

> select cast(0x5c as binary);
\
> select hex(0x5c & 0xff);
5C
> select cast(0x5c as unsigned integer);
92

我想要的结果是这样的：

> select [...] where substring(colname, N, 1) & 0b00100000 = 0b00100000;

Answer 1

尝试这样的事情：

select ascii(substring(colname,N,1)) from [...]

如何对我的 varbinary 列中的第 N 个字节执行二进制操作？

How to get do binary operations on the Nth byte in my varbinary column?

sql

binary

mariadb