mysql基础语句

#mysql在windows中字段名称不区分
#mysql在linux,unix中字段名称要区分的
#mysql中"#"是的单行注释，而"/* 注释内容  */"是多行注释。

/*
增
*/
INSERT INTO xg_role (NAME,remark) VALUES(‘赵六‘,‘赵云之弟‘);

INSERT INTO xg_role SET NAME="王五",remark="超人甲"

INSERT INTO xg_role VALUES(‘李四11‘,"路人"); #该写法除非表中只有两个字段否则是会报错滴

/*
删
delete from 表 [where] [group] [order] [limit]  
*/
DELETE FROM xg_role WHERE id = 11;

/*
改
Update 表 set 字段=值 ， 字段=值  [where] [group] [order] [limit] 
*/
UPDATE xg_role SET NAME = "jewave" WHERE id = 8

/*
 查
*/

SELECT * FROM xg_role;

SELECT COUNT(*) FROM xg_role;

SELECT AVG(id) FROM xg_role;

SELECT * FROM xg_role WHERE NAME LIKE ‘%r‘

SELECT * FROM xg_role WHERE NAME NOT LIKE‘r%‘

SELECT * FROM xg_role ORDER BY id DESC; #(正序)asc 由于默认就是正序一般省略

SELECT * FROM xg_role GROUP BY NAME; /*查询不重复项*/

SELECT * FROM xg_role WHERE id>=3 AND id<>5 #取出id大于等于3且id不等于5的所有行

SELECT * FROM xg_role WHERE NAME LIKE ‘%r‘ LIMIT 0,2 /*从查询结果截取前两条类似数学中的(0,2]*/

/*
截取 xg_role表中：id小于9且name不重复且按id倒序的前5条数据。
*/
SELECT * FROM xg_role WHERE id<9 GROUP BY NAME ORDER BY id DESC LIMIT 5;