Question

我有两张桌子说表-A和表-B

Table-A

id | Article Name |date
1  | ABC          | 25/2/2011
2  | xyz          | 26/2/2011

Table-B

id | Comment      | Article-id
1  | good         | 1
2  | nice article | 2
3  | Apreciable   | 1

所需的输出是

Table-C

id | Article Name | date       | NumberOfComments
1  | ABC          | 25/2/2011  | 2
2  | xyz          | 26/2/2011  | 1

请建议!!!

Answer 1

我认为这是你追求的问题。我没有测试它以确保没有错别字。您基本上加入了Table-B，然后将结果分组回到Table-A的结果，但计算了多少“联接”。

SELECT [Table-A].id, [Article Name], date, COUNT(*) As NumberOfComments
FROM [Table-A]
LEFT JOIN [Table-B] On [Article-id] = [Table-A].id
GROUP BY [Table-A].id, [Article Name], date

Answer 2

这样的事情应该做（未经测试，不在家）：

SELECT Table-A.id, Table-A.article-name, Table-A.date, (SELECT COUNT(id) FROM Table-B WHERE Article-id=Table-A.id) AS NumberOfComments FROM Table-A;

Answer 3

select Table_A.*, count(*) as 'NoC' from Table_A 
inner join Table_B on Table_A.id = Table_B.idart 
group by Table_A.id

从两个表中获取数据？

3 个答案: