Question

我有两个表calldetails和calltype

calldetails表

id calltype isactive
1   1       1
2   1       1
3   1       1

Calltype表

id name             isactive
1  mobile internet   1

预期结果

id name             isactive
1  mobile internet   1

但是我得到了结果

id name             isactive
1  mobile internet   1
1  mobile internet   1
1  mobile internet   1

我使用了以下查询

SELECT ct.`name` , ct.`id`
FROM calltype AS ct
INNER JOIN calldetails AS cd ON cd.`isactive` =1
WHERE ct.`isactive` =1
AND ct.`id` = cd.`calltype`
LIMIT 0 , 30

如何使用内部联接获取单个值。

Answer 1

尝试使用DISTINCT

SELECT DISTINCT ct.`name` , ct.`id`
FROM calltype AS ct
INNER JOIN calldetails AS cd ON cd.`isactive` =1
WHERE ct.`isactive` =1
AND ct.`id` = cd.`calltype`
LIMIT 0 , 30

Answer 2

在calldetails的选择中使用distinct：

SELECT ct.`name` , ct.`id`
FROM calltype AS ct
INNER JOIN (SELECT DISTINCT calltype, isactive FROM calldetails) cd ON cd.`isactive` =1
WHERE ct.`isactive` =1
AND ct.`id` = cd.`calltype`
LIMIT 0 , 30

Answer 3

尝试

SELECT ct.`name` , ct.`id`
FROM calltype AS ct
INNER JOIN calldetails AS cd ON cd.`isactive` = ct.`isactive`
WHERE ct.`isactive` =1
LIMIT 0 , 30

这是检查内部联接命令的链接： http://www.w3schools.com/sql/sql_join_inner.asp

使用内部联接获取单个值

3 个答案: