qq_21259459的博客

索引不可见alter table tableName alter index idx_name invisible;索引可见alter table tableName alter index idx_namevisible;

命令是在MySQL 5.1以后的版本中引入的。默认是禁用的，但可以通过服务器变量在会话（连接）级别动态地修改。SET profiling = 1;当一条查询提交给服务器时，此命令工具会记录剖析信息到一张临时表该统计查询返回了45670，花费了0.16秒。下面看一下SHOW PROFILES有什么结果：首先可以看到的是以很高的精度显示了查询的响应时间，这很好。MySQL客户端显示的时间只有两位小数，对于一些执行得很快的查询这样的精度是不够的。下面继续看接下来的输出：结果给出了查..

改造前SELECT * FROM `table_name` ORDER BY rand() LIMIT 1;改造后SELECT * FROM `table_name` AS t1 JOIN ( SELECT FLOOR( rand() * ( SELECT id FROM `table_name` ORDER BY id DESC LIMIT 1 )) AS id ) AS t2 WHERE t1.id >= t2.id LIMIT ...

查看 SELECT @@FOREIGN_KEY_CHECKS; 禁用 SET FOREIGN_KEY_CHECKS=0; 启用 SET FOREIGN_KEY_CHECKS=1;

Invalid default value for 'create_time'导出版本不是8存在DEFAULT '0000-00-00 00:00:00'在mysql的配置文件my.ini 中 [mysqld]下面添加如下列sql_mode=ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION重启...

登录mysqlmysql -u root -p在mysql 库中 执行ALTER USER 'root'@'%' IDENTIFIED WITH mysql_native_password BY '123456';

先登录mysqlmysql> SHOW VARIABLES LIKE 'validate_password%';+--------------------------------------+-------+| Variable_name | Value |+--------------------------------------+-------+| validate_password.check_user_name | O.

字符集-- 查询mysql 字符集相关的系统变量show variables like 'character_set%';+--------------------------+--------------------------------------------------------+| Variable_name | Value ...

这是由于mysql8 权限导致的首先进入docker 容器 4f9e173f1910662dbd4cf8d0615a145d08b2a55e9477867f4337e96c4c52ab37docker exec -ti 4f9e173f1910/bin/bash 用长的或者短的ID 都可以mysql -u root -p youpassword进入到容器之后需要...

selectconcat(table_name,">>",group_concat(COLUMN_NAME)) tfrom information_schema.COLUMNS where table_namein( select table_name from information_schema.tables where table_schema='databasenam...

查询数据库中所有表名表中数据量（不可靠：与数据库所用引擎有关）select table_name,table_rows from information_schema.tables where table_schema='databasename' order by table_rows desc; ;...