mysql数据库笔记

/*登录数据库*/
mysql -u root -p

select curdate() as 日期; 

/*两个日期相加*/
select date_add(curdate(),interval 1 month);

/*取月份，同理可取年、日*/
select month('2010-10-30');

/*取模运算*/
select mod(100,9);

/*去字符串右边的n个字符*/
select right('stinging',5);

 1.模式匹配：

 　　标准的sql模式匹配：

　　　　操作符：like 、not like

　　　　匹配符：_ 单个字符 、% 0或多个字符

　　扩展的sql模式匹配：

　　　　操作符：regexp 、 not regexp

 count() 与 group by

　　select * , count(*) from tableName  [where]  order by columnName [, columnName]

select * , count(*) from SC order by Sno;　

2.函数 SELECT function(列) [as someName]FROM 表

SELECT MAX(article) AS article FROM shop;
SELECT MIN(article) AS article FROM shop;
SELECT AVG(article) AS article FROM shop;
SELECT SUM(article) AS article FROM shop;
SELECT COUNT([DISTINCT ]article) AS article FROM shop;
SELECT COUNT(*) AS article FROM shop;

3.限制LIMIT子句　　　　　　　　　　　　　　　　　　　　　　　　　　

SELECT article, dealer, price
FROM shop
ORDER BY price DESC
LIMIT 1;

4.用户变量

SELECT @min_price:=MIN(price),@max_price:=MAX(price) FROM shop;
SELECT * FROM shop WHERE price=@min_price OR price=@max_price;

5.主要聚集函数 

count( [distinct|all] *) 
count( [distinct|all] <列名>) 
sum( [distinct|all] <列名>) 
avg( [distinct|all] <列名>) 
max ( [distinct|all] <列名>) 
min ( [distinct|all] <列名>)

参考：MySQL5.1参考手册官方简体中文版

　　http://www.w3school.com.cn/sql/sql_functions.asp