MySQL

1.命令
1.1 显示所有数据库
show databases;
1.2 选择数据库
use 数据库名
1.3 显示所有表
show tables;
1.4 刷脚本
mysql>source path+filename.sql

DELIMITER //
CREATE PROCEDURE P_REMOVE_STUDENT(IN ids VARCHAR(100),OUT result int)
BEGIN
DECLARE v_P int;# 标识ids字符串中逗号的位置
DECLARE v_Id int;# 单个id
SET v_P = INSTR(ids,",");
IF v_P = 0 THEN
DELETE FROM T_STUDENT WHERE ID=ids;
#SELECT ids;
ELSE
WHILE v_P > 0 DO
# 从第一个字符开始到逗号位置截取，但不包含逗号
SET v_Id = SUBSTRING(ids FROM 1 FOR v_P-1);

# 截取剩下的字符，但不包含逗号
SET ids = SUBSTRING(ids FROM v_P+1);
#SELECT v_Id,ids;
DELETE FROM T_STUDENT WHERE ID=v_Id;

# 获取剩下的字符中逗号的位置，以便于下一步的截取
SET v_P = INSTR(ids,",");
END WHILE;

# 循环结束后，ids中可能还有正常的数据，此时要处理
IF LENGTH(ids) > 0 THEN
DELETE FROM T_STUDENT WHERE ID=ids;
END IF;
END IF;

# 设置执行结果为成功
SET result = 1;
END
//
DELIMITER ;

dos下无法插入汉字：****************************
dos下mysql内置编译是使用gbk

所以即使你把所有的编码格式都改为utf-8

仍然需要增加一个操作,在所选数据库

使用 set names gbk; 然后再输入中文 就OK了

数据库保存的仍然为utf-8

mysql修改列名
alter table t_clazz change id clazz_id int;

远程访问数据库配置
/etc/mysql/mysql.conf.d$ sudo vi mysqld.cnf
#bind-address = 127.0.0.1 注掉

grant all privileges on *.* to 'root'@'%' identified by '123456';　　#root为远程登录用户，123456为远程登录用户的密码
flush privileges;

比如：

grant all privileges on match_info.* to 'ychs'@'192.168.1.120' identified by 'Ychs_2018' with grant option;

service mysql restart 重启服务

显示数据库编码
SHOW VARIABLES LIKE 'character%'
mysql> SHOW VARIABLES LIKE 'character%';
+--------------------------+----------------------------+
| Variable_name | Value |
+--------------------------+----------------------------+
| character_set_client | utf8 |
| character_set_connection | utf8 |
| character_set_database | latin1 |
| character_set_filesystem | binary |
| character_set_results | utf8 |
| character_set_server | latin1 |
| character_set_system | utf8 |
| character_sets_dir | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+
8 rows in set (0.00 sec)

修改编码：
[mysqld]

修改用户密码：---------------------------------------------------------------------------------------

ubuntu@VM-0-13-ubuntu:~/match$ mysqladmin -uxxx -pxxxx password xxxxx

xxx是用户名，xxxx是原密码，xxxxx是新密码

set password for 用户名@localhost = password('新密码')

查询报错---------------------------------------------------------------------------------------------------

mysql有些服务器对于count这样的统计会报错，是因为强制分组，和一个变量有关系，要修改配置文件

ubuntu@VM-0-13-ubuntu:/etc/mysql/mysql.conf.d$ 

 sudo vi mysqld.cnf 

sql_mode='STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION'

保存后，重启服务