Sql 如何连接两个不同表的列

我有两张表，分别是“概述”和“当前电压”。我想在一个表输出中获得两个不同表的前1条记录

sql查询

    select top 1  VL1,VL2,VL3 from current_voltage
    where deviceimei ='233'
    order by devicetimestamp desc      
    union
    select top 1  OTI,WTI,ATI from overview
    where deviceimei ='233'
    order by devicetimestamp desc

请求操作

VL1,VL2,VL3,OTI,WTI,ATI
234,235,234,25,24,25

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一个简单的连接就可以了。我们开始：

SELECT TOP 1 cv.VL1, cv.VL2, cv.VL3, ov.OTI, ov.WTI, ov.ATI
FROM current_voltage cv
JOIN overview ov
ON cv.deviceimei = ov.deviceimei
WHERE cv.deviceimei ='233'
ORDER BY cv.devicetimestamp DESC, ov.devicetimestamp DESC

---

要阅读有关sql中联接的更多信息，请参阅

您需要两个查询的交叉联接：

select t1.*, t2.*
from (    
    select top 1  VL1,VL2,VL3 from current_voltage
    where deviceimei ='233'
    order by devicetimestamp desc      
) t1 cross join (
    select top 1  OTI,WTI,ATI from overview
    where deviceimei ='233'
    order by devicetimestamp desc
) t2

也可以使用横向连接：

select vc.*, ov.*
from current_voltage cv cross apply
     (select top (1) ov.*
      from overview ov
      where ov.deviceimei = cv.deviceimei 
      order by ov.devicetimestamp  desc
     ) ov 
where ov.deviceimei ='233'
order by cv.devicetimestamp  desc;