SHOW COLLATION
SHOW COLLATION 语句用于提供一个静态的排序规则列表，确保与 MySQL 客户端库的兼容性。
语法图
- ShowCollationStmt
- ShowLikeOrWhere
ShowCollationStmt ::=
"SHOW" "COLLATION" ShowLikeOrWhere?
ShowLikeOrWhere ::=
"LIKE" SimpleExpr
| "WHERE" Expression
示例
若未开启新排序规则框架，仅展示二进制排序规则：
SHOW COLLATION;
+-------------+---------+------+---------+----------+---------+
| Collation | Charset | Id | Default | Compiled | Sortlen |
+-------------+---------+------+---------+----------+---------+
| utf8mb4_bin | utf8mb4 | 46 | Yes | Yes | 1 |
| latin1_bin | latin1 | 47 | Yes | Yes | 1 |
| binary | binary | 63 | Yes | Yes | 1 |
| ascii_bin | ascii | 65 | Yes | Yes | 1 |
| utf8_bin | utf8 | 83 | Yes | Yes | 1 |
+-------------+---------+------+---------+----------+---------+
5 rows in set (0.02 sec)
若开启了新排序规则框架，则在二进制排序规则之外，额外支持 utf8_general_ci 和 utf8mb4_general_ci 两种大小写和口音不敏感的排序规则：
SHOW COLLATION;
+--------------------+---------+------+---------+----------+---------+
| Collation | Charset | Id | Default | Compiled | Sortlen |
+--------------------+---------+------+---------+----------+---------+
| ascii_bin | ascii | 65 | Yes | Yes | 1 |
| binary | binary | 63 | Yes | Yes | 1 |
| gbk_bin | gbk | 87 | | Yes | 1 |
| gbk_chinese_ci | gbk | 28 | Yes | Yes | 1 |
| latin1_bin | latin1 | 47 | Yes | Yes | 1 |
| utf8_bin | utf8 | 83 | Yes | Yes | 1 |
| utf8_general_ci | utf8 | 33 | | Yes | 1 |
| utf8_unicode_ci | utf8 | 192 | | Yes | 1 |
| utf8mb4_bin | utf8mb4 | 46 | Yes | Yes | 1 |
| utf8mb4_general_ci | utf8mb4 | 45 | | Yes | 1 |
| utf8mb4_unicode_ci | utf8mb4 | 224 | | Yes | 1 |
+--------------------+---------+------+---------+----------+---------+
11 rows in set (0.001 sec)
要过滤字符集，可以添加 WHERE 子句。
SHOW COLLATION WHERE Charset="utf8mb4";
+--------------------+---------+-----+---------+----------+---------+
| Collation | Charset | Id | Default | Compiled | Sortlen |
+--------------------+---------+-----+---------+----------+---------+
| utf8mb4_0900_ai_ci | utf8mb4 | 255 | | Yes | 1 |
| utf8mb4_0900_bin | utf8mb4 | 309 | | Yes | 1 |
| utf8mb4_bin | utf8mb4 | 46 | Yes | Yes | 1 |
| utf8mb4_general_ci | utf8mb4 | 45 | | Yes | 1 |
| utf8mb4_unicode_ci | utf8mb4 | 224 | | Yes | 1 |
+--------------------+---------+-----+---------+----------+---------+
5 rows in set (0.00 sec)
MySQL 兼容性
SHOW COLLATION 语句功能与 MySQL 完全兼容。注意，TiDB 中字符集的默认排序规则与 MySQL 有所不同，具体可参考与 MySQL 兼容性对比。如发现任何其他兼容性差异，请尝试 TiDB 支持资源。