1.字符函数
length
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505112826961-1602189044.png)
concat
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505112948689-2059334296.png)
substr
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505113111632-888338866.png)
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505113158200-903510793.png)
instr
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505113316773-1116493093.png)
trim
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505113420293-308785424.png)
upper
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505113023937-1202768848.png)
lower
lpad
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505113516281-2075308106.png)
rpad
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505113543872-2122310850.png)
replace
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505113626813-1528706347.png)
2.数学函数
round
ceil
floor
truncate 截断
mod 取余
3.日期函数
now
curdate
curtime
str_to_date
date_format
4.其它函数
if
case
1.字符函数
length
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505112826961-1602189044.png)
concat
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505112948689-2059334296.png)
substr
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505113111632-888338866.png)
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505113158200-903510793.png)
instr
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505113316773-1116493093.png)
trim
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505113420293-308785424.png)
upper
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505113023937-1202768848.png)
lower
lpad
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505113516281-2075308106.png)
rpad
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505113543872-2122310850.png)
replace
![](https://img2018.cnblogs.com/blog/1479835/201905/1479835-20190505113626813-1528706347.png)
2.数学函数
round
ceil
floor
truncate 截断
mod 取余
3.日期函数
now
curdate
curtime
str_to_date
date_format
4.其它函数
if
case