sql-statement-show-indexes.md

title	summary	aliases
SHOW INDEXES [FROM|IN]	TiDB 数据库中 SHOW INDEXES [FROM|IN] 的使用概况。	/docs-cn/dev/sql-statements/sql-statement-show-indexes/ /docs-cn/dev/reference/sql/statements/show-indexes/ /zh/tidb/dev/sql-statement-show-index/ /zh/tidb/dev/sql-statement-show-keys/

SHOW INDEXES [FROM|IN]

SHOW INDEXES [FROM|IN] 语句用于列出指定表上的索引。SHOW INDEX [FROM | IN] 和 SHOW KEYS [FROM | IN] 是该语句的别名。包含该语句提供了 MySQL 兼容性。

语法图

ShowIndexStmt ::=
    "SHOW" ( "INDEX" | "INDEXES" | "KEYS" ) ("FROM" | "IN" ) TableName (("FROM" | "IN") SchemaName )? ShowLikeOrWhere?

ShowLikeOrWhere ::=
    "LIKE" SimpleExpr
|   "WHERE" Expression

示例

{{< copyable "sql" >}}

CREATE TABLE t1 (id int not null primary key AUTO_INCREMENT, col1 INT, INDEX(col1));

Query OK, 0 rows affected (0.12 sec)

{{< copyable "sql" >}}

SHOW INDEXES FROM t1;

+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | Visible | Expression |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
| t1    |          0 | PRIMARY  |            1 | id          | A         |           0 |     NULL | NULL   |      | BTREE      |         |               | YES     | NULL       |
| t1    |          1 | col1     |            1 | col1        | A         |           0 |     NULL | NULL   | YES  | BTREE      |         |               | YES     | NULL       |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
2 rows in set (0.00 sec)

{{< copyable "sql" >}}

SHOW INDEX FROM t1;

+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | Visible | Expression |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
| t1    |          0 | PRIMARY  |            1 | id          | A         |           0 |     NULL | NULL   |      | BTREE      |         |               | YES     | NULL       |
| t1    |          1 | col1     |            1 | col1        | A         |           0 |     NULL | NULL   | YES  | BTREE      |         |               | YES     | NULL       |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
2 rows in set (0.00 sec)

{{< copyable "sql" >}}

SHOW KEYS FROM t1;

+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | Visible | Expression |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
| t1    |          0 | PRIMARY  |            1 | id          | A         |           0 |     NULL | NULL   |      | BTREE      |         |               | YES     | NULL       |
| t1    |          1 | col1     |            1 | col1        | A         |           0 |     NULL | NULL   | YES  | BTREE      |         |               | YES     | NULL       |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
2 rows in set (0.00 sec)

注意为了兼容 MySQL，TiDB 在语法上支持 HASH、BTREE 和 RTREE 等索引类型，但会忽略它们。

MySQL 兼容性

SHOW INDEXES [FROM|IN] 语句与 MySQL 完全兼容。如发现任何兼容性差异，请尝试 TiDB 支持资源。

另请参阅

• SHOW CREATE TABLE
• DROP INDEX
• CREATE INDEX
• information_schema.TIDB_INDEXES
• information_schema.TIDB_INDEX_USAGE
• information_schema.KEY_COLUMN_USAGE
• sys.schema_unused_indexes