Php 如何处理select语句的除法0?
我这样做Php 如何处理select语句的除法0?,php,mysql,divide-by-zero,Php,Mysql,Divide By Zero,我这样做 $query4 = "( SELECT count(*) FROM checklist c JOIN task AS t ON t.id = c.task_id AND t.active=1 WHERE c.placement_id = m.id ) / ( SELECT cou
$query4 = "(
SELECT count(*)
FROM checklist c
JOIN task AS t ON t.id = c.task_id AND t.active=1
WHERE c.placement_id = m.id
) / (
SELECT count(*)
FROM task
WHERE active = 1
)";
在php中,我使用了一个更大的sql字符串。问题是上面的第二个选择,可能是0。如果是0,我希望除法自动变成1(比如将整个query4
变成1)
有人知道怎么做吗
谢谢。在您的情况下,最简单的更改可能是:
$query4 = "(
SELECT count(*)
FROM checklist c
JOIN task AS t ON t.id = c.placement_id AND t.active=1
WHERE c.placement_id = m.id
) / (
SELECT (case when count(*) > 0 then count(*) end)
FROM task
WHERE active = 1
)";
这会将0
值替换为NULL
——因此除法将返回NULL
,而不是错误