Using the WITH ROLLUP modifier in queries using GROUP BY will add an additional row to the result set which sums all columns. This prevents you from having you to write code which adds each column in your programming language.
Description from the Mysql Reference Manual
The GROUP BY clause allows a WITH ROLLUP modifier that causes extra rows to be added to the summary output. These rows represent higher-level (or super-aggregate) summary operations. ROLLUP thus allows you to answer questions at multiple levels of analysis with a single query. It can be used, for example, to provide support for OLAP (Online Analytical Processing) operations.
Example
1 2 3 4 5 6 7 8 | SELECT DATE(dateTime) AS order_date, count(*) AS shipments, sum(shipping_total) AS shipping_total, sum(hasShipAmt) AS hasShipAmt, sum(shipping_total)-sum(hasShipAmt) AS revenue FROM tbl_my_orders WHERE dateTime BETWEEN '$startDate' AND '$endDate 23:59:59' GROUP BY order_date WITH ROLLUP |
Tags: group by, mysql, rollup, sum columns