SQL：怎样用GROUP BY加权计数？

Question

我怎样才能做一个查询，如：

select myvalue, count() as freq from mytable group by myvalue;

但是，在freq总和值从weight柱代替计数每一行作为1？

我使用的MySQL 5.1。

Answer 1

select myvalue, sum(weight) as freq from mytable group by myvalue;

Answer 2

您要使用的总和聚合函数来处理这个问题。

SELECT MyValue, Sum(weight) AS Total
FROM mytable
GROUP BY myvalue;

应该做的伎俩！

Answer 3

select myvalue, SUM(weight) as freq from mytable group by myvalue;

Answer 4

使用sum(weight) as freq在您选择查询