sql语句的顺序

select
from
where
group by
having
order by
limit

常规函数

RTrim

LTrim

Left

Right

Length

Locate

Lower

Upper

SubString

Soundex

select name from user where Soundex(name) = Soundex('Y lie');
//有条记录name = Y lee 发音相似就会被检索出来 不知道对中文拼音如何 呵呵

日期函数

AddDate

ADDTime

CurDate

CurTime

DateDiff

Date_Add

Date_Format

Day

DayOfWeek

Hour

Minute

Month

Now

Second

Time

Year

数值处理

Abs

Cos

Exp

Mod

Pi

Rand

Sin

Sqrt

Tan

聚合函数

AVG

select avg(distinct price) as avg from products;
//思考 distinct 同样可以作用其他聚合函数 如 count 必须指定列名，sum和min也可以 不过没实际无意义

COUNT

select count(*) from tableName;  //不忽略Null值计数
select count(filedName) from tableName;  //忽略Null值计数

MAX

MIN

SUM