Name
SUM()
Synopsis
SUM([DISTINCT] expression
)
This function returns the sum of the values for the given
column or expression. It’s normally used in conjunction with a
GROUP BY
clause specifying a unique column, so that
values are compared for each unique item separately. It returns NULL
if no matching rows are found. The parameter DISTINCT
may be given
within the parentheses of the function to add only unique values found
for a given column. This parameter was added in version 5.1 of MySQL.
Here is an example:
SELECT sales_rep_id, SUM(sale_amount) AS total_sales FROM sales WHERE DATE_FORMAT(date_of_sale, '%Y%m') = DATE_FORMAT(SUBDATE(CURDATE(), INTERVAL 1 MONTH), '%Y%m') GROUP BY sales_rep_id;
This statement queries the sales
table to
retrieve only sales made during the last month. From these results,
SUM()
returns the total sale amounts
aggregated by the sales_rep_id
(see Grouping SELECT results” under the SELECT
statement in Chapter 6).
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