mysql中使用show variables同時查詢多個參數值?show variables的使用?

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需求描述:

　　今天在查mysq關於串連數的問題,想要通過一個show variables命令同時查出來多個值.在此記錄下.

操作過程:

1.通過show variables語句的like可以匹配多個值或者某個值

mysql> show variables like ‘max_connections‘;   #這裡預設的就是對Variable_name進行匹配,這裡是準確匹配.+-----------------+-------+| Variable_name   | Value |+-----------------+-------+| max_connections | 151   |+-----------------+-------+1 row in set (0.01 sec)mysql> show variables like ‘socket‘;+---------------+-----------------+| Variable_name | Value           |+---------------+-----------------+| socket        | /tmp/mysql.sock |+---------------+-----------------+1 row in set (0.00 sec)

2.通過%萬用字元進行匹配

mysql> show variables like ‘%connec%‘;      #通過百分比符號(%)這個萬用字元進行匹配,可以匹配多項.+-----------------------------------------------+-------------------+| Variable_name                                 | Value             |+-----------------------------------------------+-------------------+| character_set_connection                      | latin1            || collation_connection                          | latin1_swedish_ci || connect_timeout                               | 10                || disconnect_on_expired_password                | ON                || init_connect                                  |                   || max_connect_errors                            | 100               || max_connections                               | 151               || max_user_connections                          | 0                 || performance_schema_session_connect_attrs_size | 512               |+-----------------------------------------------+-------------------+9 rows in set (0.00 sec)

mysql> show variables like ‘innodb_thread%‘;  #%萬用字元在結束處.
+---------------------------+-------+
| Variable_name             | Value |
+---------------------------+-------+
| innodb_thread_concurrency | 0     |
| innodb_thread_sleep_delay | 10000 |
+---------------------------+-------+
2 rows in set (0.00 sec)

mysql> show variables like ‘%version‘;  #%萬用字元在開始處.
+------------------+---------------+
| Variable_name    | Value         |
+------------------+---------------+
| innodb_version   | 5.7.21        |
| protocol_version | 10            |
| tls_version      | TLSv1,TLSv1.1 |
| version          | 5.7.21-log    |
+------------------+---------------+
4 rows in set (0.00 sec)

3.使用where子句進行匹配查詢

mysql> show variables where variable_name = ‘version‘;+---------------+------------+| Variable_name | Value      |+---------------+------------+| version       | 5.7.21-log |+---------------+------------+1 row in set (0.01 sec)mysql> show variables where variable_name in (‘version‘,‘innodb_version‘);+----------------+------------+| Variable_name  | Value      |+----------------+------------+| innodb_version | 5.7.21     || version        | 5.7.21-log |+----------------+------------+2 rows in set (0.00 sec)mysql> show variables where value like ‘5.7%‘;+----------------+------------+| Variable_name  | Value      |+----------------+------------+| innodb_version | 5.7.21     || version        | 5.7.21-log |+----------------+------------+2 rows in set (0.00 sec)mysql> show variables where variable_name = ‘version‘ and value = ‘5.7‘;Empty set (0.00 sec)mysql> show variables where variable_name = ‘version‘ and value like ‘5.7%‘;+---------------+------------+| Variable_name | Value      |+---------------+------------+| version       | 5.7.21-log |+---------------+------------+1 row in set (0.00 sec)

備忘:使用where子句的方式就和在SQL語句中使用where的方式是一樣的.

 

小結:

• show variables主要是用來查看系統變數的值.
• 執行SHOW VARIABLES命令不需要任何許可權,只要求能夠串連到伺服器就可以.
• 使用like語句表示用variable_name進行匹配.

 

文檔建立時間:2018年7月17日11:33:27

mysql中使用show variables同時查詢多個參數值?show variables的使用?