資料結構
網路
RDBMS
作業系統
Java
MS Excel
iOS
HTML
CSS
Android
Python
C 程式設計
C++
C#
MongoDB
MySQL
Javascript
PHP
物理學
化學
生物學
數學
英語
經濟學
心理學
社會學
時尚研究
法律研究MySQL 中的 SHOW INDEX、SHOW INDEXES 和 SHOW KEYS 的區別？
show index、show indexes 和 show keys 沒有區別。它們有相似的含義。
我們首先建立一個表 −
mysql> create table DemoTable1549 -> ( -> EmployeeId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> EmployeeName varchar(20) -> ); Query OK, 0 rows affected (0.82 sec)
以下是建立索引的查詢 −
mysql> create index name_index1 on DemoTable1549(EmployeeName); Query OK, 0 rows affected (0.41 sec) Records: 0 Duplicates: 0 Warnings: 0
以下是 SHOW INDEX 的查詢 −
mysql> show index from DemoTable1549;
這將產生以下輸出 −
+---------------+------------+-------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+ | 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)
以下是 SHOW INDEXES 的查詢 −
mysql> show indexes from DemoTable1549;
這將產生以下輸出 −
+---------------+------------+-------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+ | 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)
以下是實施 SHOW KEYS 的查詢 −
mysql> show keys from DemoTable1549;
這將產生以下輸出 −
+---------------+------------+-------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+ | 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)
更新於： 12-12-2019
223 次瀏覽
廣告