SQL简单函数语句整理

SQL sum()

select sum(colum_name) from table_name

SQl avg()

select  avg(column_name) from table_name

SQL count()

select count(Distinct column_name) as sumNumber  from table_name   // 只是统计 不是计算加减

SQL first()

select first(column_name) as sumNumber from table_name

SQL last()

select last(column_name) as sumNumber from table_name

SQL max()

select max(column_name) from table_name

SQL min()

select max(column_name) from table_name

SQL sum()

select SUM(column_name) as sumNumber from table_name   //只是计算