理解mysql_常用經典sql
1、允許mysql遠程連接
同4
3、查看字符集設置
show variables like 'character%';
4、數據庫賦權
grant all on *.* to 'root'@'%' identified by 'Reset123QWE';
flush privileges;
grant 權限名(所有的權限用all) on 庫名(*全部).表名(*全部) to ‘要授權的用戶名’@’%’(%表示所有的IP,可以只些一個IP)
grant USAGE on cms.* to testread@'%' identified by '123456';
grant select on cms.* to testread@'%' identified by '123456';
grant all on test.* to 'testread'@'%' identified by '123456';
5、修改mysql密碼
>use mysql
>update user set password=PASSWORD('Reset123QWE') where user='root'
>flush privileges
6、看你的mysql當前默認的存儲引擎:
mysql> show variables like '%storage_engine%';
7、看你的mysql現在已提供什麼存儲引擎:
mysql> show engines;
8、查看當前隔離級別
SELECT @@tx_isolation;
9、設置全局事務隔離級別
set global transaction isolation level read committed;
set session transaction isolation level read committed;
10、導出mysql
mysqldump -uroot -pReset123QWE --all-databases > cms.sql
11、查看當前連接數配置
show variables like 'max_connections';
12、設置最大連接數
set global max_connections=1000;
13、修改my.cnf,配置最大連接數
max_connections=2000
14、獲取前1天日期
select date_sub(curdate(), interval 1 day);
15、查詢某天的日期
SELECT * FROM tb_task_info_20160301 WHERE DATE(create_time) = '2016-03-01' ORDER BY create_time DESC
16、查詢某個庫所有表的記錄數
select table_name,table_rows from tables order by TABLE_ROWS desc limit 0,100
17、忘記密碼, 用另一種方式啓動
mysqld --defaults-file="C:\mysql-5.5.39-win32\my.ini" --console --skip-grant-tables
18. 分組統計 having
SELECT domain, COUNT(id) c FROM tb_tencent_cfg_domain GROUP BY domain HAVING(c)>1
19. 過濾刪除
DELETE FROM tb_tencent_cfg_domain WHERE (`domain`, `id`) IN (
SELECT v.domain, v.id FROM
(SELECT domain, MAX(id) id FROM tb_tencent_cfg_domain GROUP BY domain HAVING COUNT(id)>1 ) v
) ;
20.查看sql是否有變化
WHERE id = #id#
and ifnull(date_format(modify_time,'%Y-%m-%d %H:%i:%s'),'') = ifnull(#modifyTime#,'');
同4
3、查看字符集設置
show variables like 'character%';
4、數據庫賦權
grant all on *.* to 'root'@'%' identified by 'Reset123QWE';
flush privileges;
grant 權限名(所有的權限用all) on 庫名(*全部).表名(*全部) to ‘要授權的用戶名’@’%’(%表示所有的IP,可以只些一個IP)
grant USAGE on cms.* to testread@'%' identified by '123456';
grant select on cms.* to testread@'%' identified by '123456';
grant all on test.* to 'testread'@'%' identified by '123456';
5、修改mysql密碼
>use mysql
>update user set password=PASSWORD('Reset123QWE') where user='root'
>flush privileges
6、看你的mysql當前默認的存儲引擎:
mysql> show variables like '%storage_engine%';
7、看你的mysql現在已提供什麼存儲引擎:
mysql> show engines;
8、查看當前隔離級別
SELECT @@tx_isolation;
9、設置全局事務隔離級別
set global transaction isolation level read committed;
set session transaction isolation level read committed;
10、導出mysql
mysqldump -uroot -pReset123QWE --all-databases > cms.sql
11、查看當前連接數配置
show variables like 'max_connections';
12、設置最大連接數
set global max_connections=1000;
13、修改my.cnf,配置最大連接數
max_connections=2000
14、獲取前1天日期
select date_sub(curdate(), interval 1 day);
15、查詢某天的日期
SELECT * FROM tb_task_info_20160301 WHERE DATE(create_time) = '2016-03-01' ORDER BY create_time DESC
16、查詢某個庫所有表的記錄數
select table_name,table_rows from tables order by TABLE_ROWS desc limit 0,100
17、忘記密碼, 用另一種方式啓動
mysqld --defaults-file="C:\mysql-5.5.39-win32\my.ini" --console --skip-grant-tables
18. 分組統計 having
SELECT domain, COUNT(id) c FROM tb_tencent_cfg_domain GROUP BY domain HAVING(c)>1
19. 過濾刪除
DELETE FROM tb_tencent_cfg_domain WHERE (`domain`, `id`) IN (
SELECT v.domain, v.id FROM
(SELECT domain, MAX(id) id FROM tb_tencent_cfg_domain GROUP BY domain HAVING COUNT(id)>1 ) v
) ;
20.查看sql是否有變化
WHERE id = #id#
and ifnull(date_format(modify_time,'%Y-%m-%d %H:%i:%s'),'') = ifnull(#modifyTime#,'');
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