Question

我要用一个联合查询2个表：

select date, A, B 
from table1 
where SERIAL_NUMBER = 1234
  and date > 'Sep 10 2018' 
  and date < 'Sep 20 2018' 

union 

select date, C, D 
from table2
where SERIAL_NUMBER = 1234
  and date > 'Sep 10 2018' 
  and date < 'Sep 20 2018' 
order by date

结果如下：

date1 a1 b1
date1 c1 d1
date2 a2 b2
date2 c2 d2

但是我想要类似的东西：

date1 a1 b1 c1 d1
date2 a2 b2 c2 d2

这可能吗？

Answer 1

然后您似乎想要join：

select t1.date, t1.a, t1.b, t2.c, t2.d
from table1 t1 join
     table2 t2
     on t1.date = t2.date and t1.serial_number = t2.serial_number
where t1.SERIAL_NUMBER = 1234 and t1.date > '2018-09-10' and t1.date < '2019-09-20'
order by t1.date;

取决于您要如何处理丢失的日期，您可能希望使用full join而不是inner join。

还要注意，我将日期格式更改为YYYY-MM-DD。这是大多数数据库认可的标准格式。

Answer 2

您无需使用UNION ALL，而不必使用JOIN。

select t1.date, t1.A, t1.B ,t2.C, t2.D 
from table1 t1 JOIN table2 t2 on t1.date = t2.date
where t1.SERIAL_NUMBER = 1234
and t1.date > 'Sep 10 2018' 
and t1.date < 'Sep 20 2018'

在SQL中按列分组并集查询

2 个答案: