| avg() |
Return numeric columns平均值 |
select avg(column_name) from table_name |
| between() |
Select 两个the data range between the values, the value can be数值文本或者日期 |
select column_name from table_name where between value1 and value1 |
| ceiling() |
向上舍入Specify the number of decimal places |
ceiling(numerical,decimal place) |
| concat |
Will be 多个字符串connected to一个字符串 |
concat(str1, str2,…) |
| concat_ws |
And the concatsame, will be 多个字符串connected 一个字符串, but you can指定分隔符 |
concat_ws(separator, str1, str2, …) |
| Count(column_name) |
Of the returned 指定列value 数目,NULL 值除外 |
select Count(column_name) from table_name |
| Count(*) |
Back in the table 记录数,包括 NULL 值 |
select Count(*) from table_name |
| Count(distict column_name) |
Returns 不同值the number of the specified column |
select Count(distict column_name) from table_name |
| cast() |
Convert some kind 数据类型of 表达式explicit to另一种数据类型 |
select cast(expression as data_type) |
| floor() |
向下舍入Specify the number of decimal places |
floor(numerical,decimal place) |
| format() |
For 字段the 显示conduct格式化 |
select format(column_name,format) from table_name |
| group by |
According to the 一个或多个列对result set进行分组 |
select group_concat(column_name,column_name) from table_name group by table_name |
| where |
Extracting those 满足指定条件of记录 |
select column_name from table_name where column_name operator value |
| if() |
条件判断Statement |
if(condition,Tlue,False) |
| limit |
Used for 限制query result return数量 |
select * from table_name limit index,quantity |
| lengh |
Obtain字符串长度 |
select lengh() |
| lcase() |
Convert 字段the value to小写 |
select lcase(column_name) from table_name |
| mid() |
From 文本字段the提取字符 |
select mid(column_name,start,[length]) from table_name |
| min () |
Returns the specified column最小值 |
select min(column_name) from table_name |
| max() |
Returns the specified column最大值 |
select max(column_name) from table_name |
| round() |
四舍五入Convert the original value to the specified number of decimal places |
round(numerical,decimal place) |
| Rand() |
随机函数A random 0到1number |
select Rand() |
| select |
From 数据库selecting the数据 |
select 数据名 from 数据库名 |
| select disstinct |
Used to return唯一不同的值 |
select disstinct column_name,column_name from table_name |
| show |
List 数据库系统all数据库 |
show databases or tables |
| substr |
String interception内容 |
substr(str,start,end) |
| Sum() |
Return numeric columns总数 |
select Sum(column_name) from table_name |
| Sleep() |
休眠 |
select slepp ( time) |
| top() |
For 规定the record to be returned数目 |
select top (numerical *) or (numericalpercent) from name |
| use |
Change current operation数据库 |
use 数据库名 |
| ucase() |
Convert 字段the value to大写 |
select ucase(column_name) from table_name |
| union |
Merged 两个or 多个 SELECT 语句result |
select column_name,… from table_name union select ..... |
| union all |
Allowable on the basis of union选取重复的值 |
select column_name,… from table_name union all select ..... |