我有一张书桌,上面有一些书评;
这些是我为测试这个查询而创建的一些虚拟记录;
ID BookID RatersID Rating Date
1 2 3 5 (date)
2 2 4 4 (date)
SELECT `RatersID`,
COUNT(*) AS `raters`, `Rating`, COUNT(*) AS `Ratings`
FROM
`BOOKS_ratings`
GROUP BY
`BookID`
当我运行我期望的查询时
BookID Raters Ratings
2 2 9
我得到的是:
RatersID raters Rating Ratings
3 2 5 2
我不明白为什么会这样?
///////////////////上面已经回答了
我已经让查询工作了,但是当试图用php接收信息时,数字是重复的
例如Raters=2 PHP显示22
评分=9 PHP显示99
$getratingq = mysqli_query($con,"SELECT `RatersID`, COUNT(*) AS `Raters`, sum(Rating) AS `Ratings` FROM `BOOKS_ratings` WHERE `BookID` ='$bookid' GROUP BY `BookID` LIMIT 1") or die("Get ratings query error");
if($getrating = mysqli_fetch_array($getratingq))
{
echo $ratings = $getrating['Ratings'];
$raters= $getrating['Raters'];
$rating = $ratings/$raters;
$stars = floor("$rating");
}
最佳答案
您需要使用sum()
来获得评分的总和
SELECT
`BookID`,
COUNT(*) AS `raters`
sum(Rating) as Ratings
FROM
`BOOKS_ratings`
GROUP BY
`BookID`