SQL: how to get a weighted count using GROUP BY?

How can I make a query like:

select myvalue, count() as freq fro开发者_Python百科m mytable group by myvalue;

But where freq sums values from a weight column instead of counting each row as 1?

I'm using MySQL 5.1.

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You want to use the Sum aggregate function to handle this.

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

Should do the trick!

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

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

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use sum(weight) as freq in your select query