Aggregate function and other columns

问题

Is it possible for a SQL query to return some normal columns and some aggregate ones?

like :

Col_A | Col_B | SUM
------+-------+------
   5  |   6   |  7

回答1:

You should use the group by statement.

The GROUP BY statement is used in conjunction with the aggregate functions to group the result-set by one or more columns.

For example:

SELECT column_name, aggregate_function(column_name)
FROM table_name
WHERE column_name operator value
GROUP BY column_name

You can see a complete example here.

回答2:

Yes of course. Read on GROUP BY and aggregate functions. e.g.

SELECT col1, col2, SUM(col3) 
FROM table 
GROUP BY col1, col2

回答3:

Yes, add them to GROUP BY clause.

回答4:

If you GROUP BY some fields, you can show those fields, and aggregate others; e.g.:

SELECT colA, colB, SUM(colC)
FROM TheTable
GROUP BY colA, colB

aggregation can be by SUM, MIN, MAX, etc.

回答5:

You can show ordinary columns or expressions based on ordinary columns, but only if they are included in the set of columns/expressions you are agregating over ( what is listed in Group By clause ).

来源：https://stackoverflow.com/questions/1249125/aggregate-function-and-other-columns