一个sql语句的写法

[y63964632]

表a
id int
content varchar(200)
flag int

表b

id int
userID int
tel varchar(10)
flag int

insert into a values(1,'Nice to Meet you!',0)

insert into b values(1,123,'13812345678',0)
insert into b values(2,124,'13912345678',0)
insert into b values(3,125,'13712345678',0)

要求得到结果

13812345678 Nice to Meet you!
13912345678 Nice to Meet you!
13712345678 Nice to Meet you!

但是如果 表中flag都为1 则无结果

例如：

insert into a values(1,'Nice to Meet you!',1)

insert into b values(1,123,'13812345678',0)
insert into b values(2,124,'13912345678',0)
insert into b values(3,125,'13712345678',0)

查询无结果

insert into a values(1,'Nice to Meet you!',0)

insert into b values(1,123,'13812345678',1)
insert into b values(2,124,'13912345678',0)
insert into b values(3,125,'13712345678',0)

结果只有俩条

13912345678 Nice to Meet you!
13712345678 Nice to Meet you!

我这么写了

SELECT b.tel,content
FROM a left JOIN
b on a.flag=0 and b.flag =0

但是 如果 a表的flag为1以后 还是有一条这样的结果

null Nice to meet you!

应该怎么写比较合理呢？

[黄_瓜]

select tel,'Nice to Meet you!' from b

[百年树人]

SELECT b.tel,content
FROM  a    
JOIN  b on a.flag=b.flag and a.flag =0 

[ws_hgo]

a表的信息了............

[黄_瓜]

select b.tel,a.content from b 
left join a on a.flag =b.flag or a.flag <>b.flag

[y63964632]

引用 1 楼 beirut 的回复:

SQL codeselect tel,'Nice to Meet you!'from b

主要是和flag有关系 和nice to meet you 没关系
大哥

如果俩个表中flag为0的数据连接起来

[黄_瓜]

你到底要啥结果？
不管flag为0不为0 都显示3条吗？

[SQL77]

SELECT b.tel,content
FROM a left JOIN
b on a.flag=0 and b.flag =0

把LEFT 去掉

[黄_瓜]

引用 5 楼 y63964632 的回复:

引用 1 楼 beirut 的回复:SQL codeselect tel,'Nice to Meet you!'from b

主要是和flag有关系 和nice to meet you 没关系
大哥

如果俩个表中flag为0的数据连接起来

--try
select b.tel,a.content from b 
left join a on a.flag =b.flag or a.flag=0

[y63964632]

谢谢了 去掉left就行了

[ws_hgo]

引用 9 楼 y63964632 的回复:

谢谢了 去掉left就行了

GX.............

[快乐_石头]