Question

你好我有这样的表：

表格条目：

id | TOTAL_COMMENTS
_____________________
1 | 0
2 | 0
3 | 0
4 | 0

表评论：

id |开斋节评论
_____________________
1 | 1 |评论sdfd
2 | 1 |测试测试
3 | 1 |评论文本
4 | 2 |虚假评论
5 | 2 |样本评论
6 | 1 | fg fgh dfh

我写的查询：

UPDATE entry 
   SET total_comments = total_comments + 1 
 WHERE id IN ( SELECT eid 
                 FROM comments 
                WHERE id IN (1,2,3,4,5,6))

我得到的结果是：

表格条目：

id | TOTAL_COMMENTS
_____________________
1 | 1
2 | 1
3 | 0
4 | 0

预期结果：

表格条目：

id | TOTAL_COMMENTS
_____________________
1 | 4
2 | 2
3 | 0
4 | 0

任何帮助将不胜感激。

Answer 1

使用：

UPDATE entry 
   SET total_comments = (SELECT COUNT(*)
                           FROM COMMENTS c
                          WHERE c.eid = id
                       GROUP BY c.eid)
 WHERE id IN ( SELECT eid 
                 FROM comments 
                WHERE id IN (1,2,3,4,5,6))

Answer 2

如果你真的需要在一个单独的表中使用total_comments，我会把它作为一个VIEW。

CREATE VIEW entry AS 
  SELECT id, COUNT(comments) AS total_comment 
  FROM comments 
  GROUP BY id

这样就可以避免完全更新total_comments表的维护任务。

Answer 3

这正是我所期待的。 id是你给它的集合，所以total_comments = total_comments + 1。

它不会为每个具有相同值的实例添加一个：这不是IN的工作方式。 IN将返回一个简单的布尔值yes / no。

Answer 4

尝试：

UPDATE entry
  SET total_comments = (SELECT COUNT(*) 
                        FROM comments
                        WHERE entry.id = comments.eid
                        GROUP BY id)

Answer 5

UPDATE entry e 
    SET total_comments = ( SELECT COUNT(*) FROM comments WHERE eid = e.id)  
    WHERE 
    e.id in (SELECT eid FROM comments WHERE id IN (1,2,3,4,5,6))

使用IN和子查询进行MYSQL更新

5 个答案: