MySQL中的SHOW INDEX，SHOW INDEXES和SHOW KEYS之间的区别？
showindex，showindex和showkey之间没有区别。它们具有相似的含义。
让我们首先创建一个表-
create table DemoTable1549 -> ( -> EmployeeId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> EmployeeName varchar(20) -> );
以下是创建索引的查询-
create index name_index1 on DemoTable1549(EmployeeName); Records: 0 Duplicates: 0 Warnings: 0
以下是查询SHOWINDEX-
show index from DemoTable1549;
这将产生以下输出-
+---------------+------------+-------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+ | Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | Visible | +---------------+------------+-------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+ | demotable1549 | 0 | PRIMARY | 1 | EmployeeId | A | 0 | NULL | NULL | | BTREE | | | YES | | demotable1549 | 1 | name_index1 | 1 | EmployeeName | A | 0 | NULL | NULL | YES | BTREE | | | YES | +---------------+------------+-------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+ 2 rows in set (0.17 sec)
这是SHOWINDEXES的查询-
show indexes from DemoTable1549;
这将产生以下输出-
+---------------+------------+-------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+ | Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | Visible | +---------------+------------+-------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+ | demotable1549 | 0 | PRIMARY | 1 | EmployeeId | A | 0 | NULL | NULL | | BTREE | | | YES | | demotable1549 | 1 | name_index1 | 1 | EmployeeName | A | 0 | NULL | NULL | YES | BTREE | | | YES | +---------------+------------+-------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+ 2 rows in set (0.00 sec)
这是实现SHOWKEYS的查询-
show keys from DemoTable1549;
这将产生以下输出-
+---------------+------------+-------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+ | Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | Visible | +---------------+------------+-------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+ | demotable1549 | 0 | PRIMARY | 1 | EmployeeId | A | 0 | NULL | NULL | | BTREE | | | YES | | demotable1549 | 1 | name_index1 | 1 | EmployeeName | A | 0 | NULL | NULL | YES | BTREE | | | YES | +---------------+------------+-------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+ 2 rows in set (0.00 sec)