使用WHERE IN时如何获取每个项目的计数

Question

我有一个表评论

我正在查询

SELECT * FROM comment WHERE coupon_id IN (28,14,56);

我想选择每张优惠券的所有评论和评论总数 [优惠券ID为（28,14,56）]

请查看SQLFiddle Showing the Query

Answer 1

  

我想选择每张优惠券的评论总数[优惠券ID为（28,14,56）]

您需要使用GROUP BY：

SELECT
    coupon_id,
    COUNT(*)
FROM
    comment
WHERE
    coupon_id IN (28,14,56)
GROUP BY
    coupon_id;

如果您想获得评论的数量以及所有评论，您必须使用子查询：

SELECT 
    *,
    (SELECT 
           COUNT(*) 
     FROM 
          `comment` AS cnt_comment 
     WHERE 
          cnt_comment.coupon_id=comment.coupon_id
    ) AS total_comments
FROM 
     `comment` 
WHERE 
     coupon_id IN (28,14);

sqlfiddle

Answer 2

使用GROUP BY。试试 -

SELECT 
    *, COUNT(comment_id) AS total_comment 
FROM comment 
WHERE coupon_id IN (28,14,56) 
GROUP BY coupon_id 

如果您不想要所有列并指定所需的列，请删除*。