UC知道求助：SQL语句
来源：百度知道 编辑：UC知道 时间：2024/05/18 09:13:20
要从JOB表取出若干字段，比如A1,A2,A3. 在JOB表中数据，如果A2的值=‘Y’，这个字段的值是空的。
这种情况下，要从Address表中，取相应的值，取值条件是JOB.A1=Address.A1 ,取出Address.A3.
JOB
A1 A2 A3
--- --- ---
100 N 123
200 N 456
300 Y ‘ ’
Address
A1 A3
--- ---
300 588
输出结果
A1 A2 A3
--- --- ---
100 N 123
200 N 456
300 Y 588
这样的SQL语句该怎么写呀。
注：不想用Decode函数实现。
谢谢各位大虾了。！！！
这种情况下，要从Address表中，取相应的值，取值条件是JOB.A1=Address.A1 ,取出Address.A3.
JOB
A1 A2 A3
--- --- ---
100 N 123
200 N 456
300 Y ‘ ’
Address
A1 A3
--- ---
300 588
输出结果
A1 A2 A3
--- --- ---
100 N 123
200 N 456
300 Y 588
这样的SQL语句该怎么写呀。
注：不想用Decode函数实现。
谢谢各位大虾了。！！！
select a.A1,A.a2,case when a.A2='Y' then b.A3 else a.A3 end as A3
from JOB a inner join Address b on a.A1 = b.A1;
---
以上，希望对你有所帮助。
select job.a1 as a1,job.a2 as a2,job.a3 as a3
from job left adress on job.a1=adress.a1
union all
select adress.a1 as a1,adress.a2 as a2,adress.a3 as a3
from job left adress on job.a1=adress.a1
select a1,a2,a3 from job where a2='n'
union
select a.a1,a.a2,b.a3 from job a,adress b where a.a2='y';
select a1,a2,a3 from job where a2='n'
union
select a.a1,a.a2,b.a3 from job a,adress b where a.a2='y';