mysql常用语法

Posted 2021-01-31 wang_zai

1. DISTINCT用法

#SELECT DISTINCT store_name FROM db.MY WHERE Sales>1000;

2.AND OR 用法

#SELECT store_name,Sales FROM db.MY WHERE Sales>1000 OR (Sales<500 AND Sales>275);

3.IN用法

#SELECT * FROM db.MY WHERE store_name IN (‘Los Angeles‘,‘wangzai‘);

4.Between and 用法

#SELECT * FROM db.MY WHERE date BETWEEN ‘Jan-07-1999‘ AND ‘Jan-08-1999‘;

5.LIKE用法

#SELECT * FROM db.MY WHERE store_name LIKE ‘%ge%‘;

6.ORDER BY用法

#SELECT * FROM db.MY ORDER BY Sales;

#SELECT store_name,Sales,date from db.MY ORDER BY 2 DESC;

7.SUM用法

#SELECT SUM(Sales) FROM db.MY;

8.COUNT用法

#SELECT COUNT(store_name) FROM db.MY WHERE store_name is NOT NULL;

#SELECT COUNT(DISTINCT store_name) FROM db.MY WHERE store_name is NOT NULL;

9.GROUP BY 用法

#SELECT store_name,SUM(Sales) FROM db.MY GROUP BY store_name;

10.HAVING 用法

#SELECT store_name,SUM(Sales) FROM db.MY GROUP BY store_name HAVING SUM(Sales)>1500;

11.ALIAS 别名用法

#SELECT A1.store_name Store,SUM(A1.Sales) "Total Sales" FROM db.MY A1 GROUP BY Store;

11.表格链接 用法

#SELECT A1.region_name REGION,SUM(A2.Sales) SALES FROM db.Geography A1,db.MY A2

#WHERE A1.store_name1=A2.store_name GROUP BY A1.region_name;

12.CONCAT 连接字符串用法

#SELECT CONCAT(region_name,store_name1) FROM db.Geography WHERE store_name1=‘Boston‘;

12.SUBSTR 抓取部分字符 用法

#SELECT SUBSTR(store_name1,3) FROM Geography WHERE store_name1=‘Los Angeles‘;

#SELECT SUBSTR(store_name1,2,4) FROM Geography WHERE store_name1=‘San Diego‘;

13.创建表

#CREATE TABLE Customer

#(Sid INTEGER UNIQUE,

#First_Name char(50) NOT NULL,

#Last_Name char(50));

14.给表中的字段添加UNIQUE 唯一值

#ALTER TABLE Customer add UNIQUE key(`Sid`);

15.创建表的同时创建主键

#CREATE TABLE Customer1

#(Sid integer,

#Last_Name VARCHAR(30),

#First_Name VARCHAR(30),

#PRIMARY KEY (Sid));

16.给表中字段增加主键

#ALTER TABLE Customer ADD PRIMARY KEY (Sid);

17.创建表的同时创建外键

#CREATE TABLE Orders

#(Order_ID integer,

#Order_Date date,

#Customer_SID integer,

#Amount double,

#Primary Key (Order_ID),

#Foreign Key (Customer_SID) references Customer(Sid));

18.给表中字段添加外键

#ALTER TABLE Orders

#ADD FOREIGN KEY (Customer_sid) REFERENCES Customer(Sid);

 

19.创建视图

#CREATE VIEW V_REGION_SALES

#AS SELECT A1.region_name REGION,SUM(A2.Sales) SALES FROM db.Geography A1,db.MY A2

#WHERE A1.store_name1=A2.store_name GROUP BY A1.region_name;

20.查询视图

#SELECT * FROM V_REGION_SALES

21.创建索引

#CREATE INDEX IDX_Customer_Location on customer(City,Country)

22.给表中添加字段

#ALTER TABLE customer add Gender char(1);

23.修改表中字段的名字

#ALTER TABLE customer CHANGE Address Addr char(50);

24.修改表中字段的数据类型

#ALTER TABLE customer MODIFY Addr char(30);

25.删除表中某个字段

#ALTER TABLE customer DROP Gender;

26.mysql查询最后一条语句

#select id,name from uc_user order by id desc limit 0,1;

27. 其中记录 NULL 表示所有人的登录次数。我们可以使用 coalesce 来设置一个可以取代 NUll 的名称，coalesce 语法：

#SELECT coalesce(name, ‘Total_sum‘), SUM(singin) as singin_count FROM  employee_tbl GROUP BY name WITH ROLLUP;

28.修改表名

#ALTER TABLE wangzai RENAME to doubi;

29.把本地数据插入到mysql表中

LOAD DATA LOCAL INFILE “/root/1.txt” INTO TABLE test;