二进制字符串是字节序列。对于binary 排序规则，比较和排序基于数字字节值。非二进制字符串是字符序列，可能为多字节。非二进制字符串的排序规则定义了字符值的比较和排序顺序。对于_bin 排序规则，这种顺序基于数字字符码值，这与二进制字符串的排序类似，只是字符码值可能为多字节。Binary strings are sequences of bytes. For the binary collation, comparison and sorting are based on numeric byte values. Nonbinary strings are sequences of characters, which might be multibyte. Collations for nonbinary strings define an ordering of the character values for comparison and sorting. For _bin collations, this ordering is based on numeric character code values, which is similar to ordering for binary strings except that character code values might be multibyte.

一个非二进制字符串有一个字符集，并且在许多情况下会自动转换为另一种字符集，即使该字符串有一个 _bin 校对规则：A nonbinary string has a character set and is automatically converted to another character set in many cases, even when the string has a _bin collation:

对于二进制字符串列，不进行任何转换。对于类似前述情况的，字符串值按字节复制。For binary string columns, no conversion occurs. For cases similar to those preceding, the string value is copied byte-wise.

非二进制字符集的排序规则提供字符的大小写信息，因此非二进制字符串中的字符可以从一种字母大小写转换为另一种字母大小写，即使对于忽略排序中字母大小写的 _bin 排序规则也是如此：Collations for nonbinary character sets provide information about lettercase of characters, so characters in a nonbinary string can be converted from one lettercase to another, even for _bin collations that ignore lettercase for ordering:

mysql> SET NAMES utf8mb4 COLLATE utf8mb4_bin;
mysql> SELECT LOWER('aA'), UPPER('zZ');
+-------------+-------------+
| LOWER('aA') | UPPER('zZ') |
+-------------+-------------+
| aa          | ZZ          |
+-------------+-------------+

字母大小写的概念不适用于二进制字符串中的字节。要进行字母大小写转换，必须首先使用适合存储在字符串中的数据的字符集将字符串转换为非二进制字符串：The concept of lettercase does not apply to bytes in a binary string. To perform lettercase conversion, the string must first be converted to a nonbinary string using a character set appropriate for the data stored in the string:

mysql> SET NAMES binary;
mysql> SELECT LOWER('aA'), LOWER(CONVERT('aA' USING utf8mb4));
+-------------+------------------------------------+
| LOWER('aA') | LOWER(CONVERT('aA' USING utf8mb4)) |
+-------------+------------------------------------+
| aA          | aa                                 |
+-------------+------------------------------------+

MySQL 排序规则具有 pad 属性，其值为 PAD SPACE 或 NO PAD：MySQL collations have a pad attribute, which has a value of PAD SPACE or NO PAD:

对于非二进制字符串（CHAR、VARCHAR 和 TEXT 值），字符串排序规则的 pad 属性决定了在比较字符串末尾尾随空格时的处理方式：For nonbinary strings (CHAR, VARCHAR, and TEXT values), the string collation pad attribute determines treatment in comparisons of trailing spaces at the end of strings:

不同的行为可以通过使用两个 utf8mb4 二进制排序规则来演示，其中一个是 PAD SPACE，另一个是 NO PAD。该示例还展示了如何使用 INFORMATION_SCHEMA COLLATIONS 表来确定排序规则的填充属性。The differing behaviors can be demonstrated using the two utf8mb4 binary collations, one of which is PAD SPACE, the other of which is NO PAD. The example also shows how to use the INFORMATION_SCHEMA COLLATIONS table to determine the pad attribute for collations.

mysql> SELECT COLLATION_NAME, PAD_ATTRIBUTE
       FROM INFORMATION_SCHEMA.COLLATIONS
       WHERE COLLATION_NAME LIKE 'utf8mb4%bin';
+------------------+---------------+
| COLLATION_NAME   | PAD_ATTRIBUTE |
+------------------+---------------+
| utf8mb4_bin      | PAD SPACE     |
| utf8mb4_0900_bin | NO PAD        |
+------------------+---------------+
mysql> SET NAMES utf8mb4 COLLATE utf8mb4_bin;
mysql> SELECT 'a ' = 'a';
+------------+
| 'a ' = 'a' |
+------------+
|          1 |
+------------+
mysql> SET NAMES utf8mb4 COLLATE utf8mb4_0900_bin;
mysql> SELECT 'a ' = 'a';
+------------+
| 'a ' = 'a' |
+------------+
|          0 |
+------------+

对于二进制字符串（BINARY、VARBINARY 和 BLOB 值），比较时所有字节都是重要的，包括末尾空格：For binary strings (BINARY, VARBINARY, and BLOB values), all bytes are significant in comparisons, including trailing spaces:

mysql> SET NAMES binary;
mysql> SELECT 'a ' = 'a';
+------------+
| 'a ' = 'a' |
+------------+
|          0 |
+------------+

CHAR(N) 列存储长度为 N 个字符的非二进制字符串。对于插入操作，长度短于 N 个字符的值将用空格进行扩展。对于检索操作，会移除尾随空格。CHAR(N) columns store nonbinary strings N characters long. For inserts, values shorter than N characters are extended with spaces. For retrievals, trailing spaces are removed.

BINARY(N) 列存储长度为 N 个字节的二进制字符串。对于插入操作，长度短于 N 个字节的值将用 0x00 字节进行扩展。对于检索操作，不会移除任何内容；始终返回声明长度的值。BINARY(N) columns store binary strings N bytes long. For inserts, values shorter than N bytes are extended with 0x00 bytes. For retrievals, nothing is removed; a value of the declared length is always returned.

mysql> CREATE TABLE t1 (
         a CHAR(10) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin,
         b BINARY(10)
       );
mysql> INSERT INTO t1 VALUES ('x','x');
mysql> INSERT INTO t1 VALUES ('x ','x ');
mysql> SELECT a, b, HEX(a), HEX(b) FROM t1;
+------+------------------------+--------+----------------------+
| a    | b                      | HEX(a) | HEX(b)               |
+------+------------------------+--------+----------------------+
| x    | 0x78000000000000000000 | 78     | 78000000000000000000 |
| x    | 0x78200000000000000000 | 78     | 78200000000000000000 |
+------+------------------------+--------+----------------------+