文法
SHOW {INDEX | INDEXES | KEYS}
{FROM | IN} tbl_name
[{FROM | IN} db_name]
[WHERE expr]
示例
mysql> show index from t_order;
+--------------+------------+-----------+--------------+----------------+-----------+-------------+----------+--------+------+------------+----------+---------------+
| TABLE | NON_UNIQUE | KEY_NAME | SEQ_IN_INDEX | COLUMN_NAME | COLLATION | CARDINALITY | SUB_PART | PACKED | NULL | INDEX_TYPE | COMMENT | INDEX_COMMENT |
+--------------+------------+-----------+--------------+----------------+-----------+-------------+----------+--------+------+------------+----------+---------------+
| t_order | 0 | PRIMARY | 1 | id | A | 0 | NULL | NULL | | BTREE | | |
| t_order | 1 | l_i_order | 1 | order_id | A | 0 | NULL | NULL | YES | BTREE | | |
| t_order | 0 | g_i_buyer | 1 | buyer_id | NULL | 0 | NULL | NULL | YES | GLOBAL | INDEX | |
| t_order | 1 | g_i_buyer | 2 | id | NULL | 0 | NULL | NULL | | GLOBAL | COVERING | |
| t_order | 1 | g_i_buyer | 3 | order_id | NULL | 0 | NULL | NULL | YES | GLOBAL | COVERING | |
| t_order | 1 | g_i_buyer | 4 | order_snapshot | NULL | 0 | NULL | NULL | YES | GLOBAL | COVERING | |
+--------------+------------+-----------+--------------+----------------+-----------+-------------+----------+--------+------+------------+----------+---------------+
6 rows in set (0.01 sec)
表 1. 列名說明
列名 | 說明 |
TABLE | 表名 |
NON_UNIQUE | 是否為唯一限制全局二級索引,取值範圍如下:
|
KEY_NAME | 索引名 |
SEQ_IN_INDEX | 索引列在索引中的序号,取值從1開始。 |
COLUMN_NAME | 索引列名。 |
COLLATION | 排序方式,取值範圍如下:
|
CARDINALITY | 預計的唯一值數目 |
SUB_PART | 索引字首(NULL索引字首為整個列)。 |
PACKED | 字段壓縮資訊(NULL表示沒有壓縮)。 |
NULL | 是否允許空。 |
INDEX_TYPE | 索引類型,取值範圍如下:
|
COMMENT | 索引資訊,取值範圍如下:
|
INDEX_COMMENT | 其他資訊 |