查看编码格式
SHOW VARIABLES LIKE 'character_set_%';
+--------------------------+--------------------------------+
| Variable_name | Value |
+--------------------------+--------------------------------+
| character_set_client | gbk |
| character_set_connection | gbk |
| character_set_database | latin1 |
| character_set_filesystem | binary |
| character_set_results | gbk |
| character_set_server | latin1 |
| character_set_system | utf8 |
| character_sets_dir | C:\xampp\MysqL\share\charsets\ |
+--------------------------+--------------------------------+
设置编码格式：
set character_set_server='utf8';
set character_set_database='utf8';
set collation_database='utf8_general_ci';
set collation_server='utf8_general_ci';
查看混排编码
SHOW VARIABLES LIKE 'collation_%';
+----------------------+-------------------+
| Variable_name | Value |
+----------------------+-------------------+
| collation_connection | gbk_chinese_ci |
| collation_database | latin1_swedish_ci |
| collation_server | latin1_swedish_ci |
+----------------------+-------------------+
查看数据库编码
show create database smallgarden;
+-------------+---------------------------------------------------------------------------------------+
| Database | Create Database |
+-------------+---------------------------------------------------------------------------------------+
| smallgarden | CREATE DATABASE smallgarden /!40100 DEFAULT CHARACTER SET utf8 COLLATE utf8_bin / |
+-------------+---------------------------------------------------------------------------------------+
查看表编码
show create table user;
+-------+-------------------------------------------
| user | CREATE TABLE user (
id varchar(255) NOT NULL,create_time datetime NOT NULL,last_login_time datetime DEFAULT NULL,name varchar(32) DEFAULT NULL,password varchar(64) DEFAULT NULL,tel varchar(20) DEFAULT NULL,user_type varchar(64) DEFAULT NULL,org_id varchar(255) DEFAULT NULL,PRIMARY KEY (id),UNIQUE KEY UK_0dd127af0d0a4614b2d720e3911 (name),KEY FK_f06ddcc41db2421899305d5e8aa (org_id),CONSTRAINT FK_f06ddcc41db2421899305d5e8aa FOREIGN KEY (org_id) REFERENCES org (id)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+-------------------------------------------
MysqL如何修改unique key
MysqL可以使用unique key来确保数据的准确性，unique key可以是一个字段，也可以是多个字段，
对应已经存在的unique key如何修改呢？目前我使用的方法是分两步来完成，先drop掉，然后在创建。
需要注意的是drop时关键字是“index”，而创建时关键词是“unique key”，命令如下：
alter table table_name drop index uk_name;
alter table table_name add unique key new_uk_name (col1,col2);
注意：如果表中已经存在数据，可能会创建失败，原因是col1,col2无法满足unique。
MysqL 修改字段长度
alter table news modify column title varchar(130);
alter table 表名 modify column 字段名 类型;
MysqL删除字段
alter table user_movement_log drop column Gatewayid
