Question

如何在以下查询中添加百分比列？我想在第四列中显示相应的（升级/ needsupgrade * 100），但这会返回＆＃34; 0＆＃34;在＆＃34;百分比＆＃34;柱：

SELECT
    upgraded,
    needsupgrade,
    total,
    upgraded / needsupgrade * 100 AS 'percent done'
FROM
(
    SELECT count(id) AS upgraded
    FROM attempts
    WHERE needsupgrade = 1
) upgraded,
(
    SELECT count(id) AS needsupgrade
    FROM attempts
    WHERE needsupgrade = 0
) needsupgrade,
(
    SELECT count(id) AS total
    FROM attempts
) total

Answer 1

这可能是由于SQL Server在对整数进行分割时返回一个整数在你的情况下，这可能是0，你需要将至少一个字段转换为十进制。

SELECT
    upgraded,
    needsupgrade,
    total,
    (upgraded / convert(decimal, needsupgrade)) * 100 AS 'percent done'
FROM
(
    SELECT count(id) AS upgraded
    FROM attempts
    WHERE needsupgrade = 1
) upgraded,
(
    SELECT count(id) AS needsupgrade
    FROM attempts
    WHERE needsupgrade = 0
) needsupgrade,
(
    SELECT count(id) AS total
    FROM attempts
) total

Answer 2

int除以和int将返回一个int

只需为计算添加一些精度

(upgraded / (needsupgrade+0.0)) * 100 AS 'percent done'

例如

Select 25/100 Returns 0
While
Select 25/(100+.0) Returns 0.25

添加平均列

2 个答案: