php - 从一列中减去另一列的总数 - PHP/MySQL

Question

我正在尝试做的是从另一整列的总数中减去一整列 MySQL 列的总数。我可以分别成功地对两列求和，但我无法弥合将它们相加然后从另一列中减去一列之间的差距。

$start = "SELECT SUM(start) FROM `table`";
$end = "SELECT SUM(end) FROM `table`";
$total = "Here is my problem"; //I tried something like $end - $start, but to no avail

我可以显示开始的总和和结束的总和，但不能取结束-开始。

Answer 1

你试过吗:

SELECT (SUM(start) - SUM(end)) AS `difference` FROM `table`