mysql函数大全-简单的总结，便于记忆_MySQL
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mysql函数大全-简单的总结，便于记忆
简单的总结，便于记忆。
日期时间函数：
NOW()-------------------------------系统当前的日期时间
year()------------------------------返回一个日期的年份部分
month()-----------------------------返回一个日期的月份部分
Date() -----------------------------返回日期时间的日期部分
Day() ------------------------------返回一个人日期的天数部分
Dayofweek()-------------------------返回一个日期对应的星期部分
hour() -----------------------------返回一个时间的小时部分
minute()----------------------------返回一个时间的分钟部分
second()----------------------------返回一个时间的秒部分
CurTime()---------------------------返回当前的时间
CurDate()---------------------------返回当前日期
Day-format()------------------------返回一个格式化的日期时间字符串
AddDate()---------------------------增加一个日期（天，周等）
AddTime()---------------------------增加一个时间（时，分等）
DateDiff()--------------------------计算两个日期之差
Date_add()--------------------------高度灵活的日期运算函数
日常文本函数
left()-----------------------------返回左边的字符串
right()----------------------------返回右边的字符串
Ltrim()----------------------------去掉左边的空格
Rtrim()----------------------------去掉右边的空格
Trim()-----------------------------去掉两边的空格
upper()-----------------------------将字符串转换成大写
lower()-----------------------------将字符串转换成小写
length()----------------------------返回字符串的长度
locate()----------------------------找出串的一个子串
substring()-------------------------返回子串
soundex()---------------------------返回串的soundex的值
数值处理函数
Abs()------------------------------绝对值
sqrt()-----------------------------开平方根
sin()------------------------------正玄函数
tan()------------------------------正切喊杀声
rand()-----------------------------返回一个随机数
cos()------------------------------余玄函数
mod()------------------------------返回除以一个数的余数
exp()------------------------------返回一个数的指数值
pi()-------------------------------返回圆周率
select 10 mod(3)-------------------计算10除以3的模
聚集函数（组函数）
cont()-----------------------------计算某列的行数
max()------------------------------计算某列的最大值
min()------------------------------计算某列的最小值
sum()------------------------------计算某列的和
avg()------------------------------计算某列的平均值
select子句的顺序
select
from
where
group by
having
orde by
limit
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