根据A表中的不同字段，连接B表中的不同行。

以下例子，表x是8仓换电柜的信息，包含8个仓中的电池编号，表y是电池的信息，现在需要两个表部分信息合并，将x中的电池编号与y中的相同编号的电池数据并在一行。

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select
x.*
,y1.val6 as soc1
,y2.val6 as soc2
,y3.val6 as soc3
,y4.val6 as soc4
,y5.val6 as soc5
,y6.val6 as soc6
,y7.val6 as soc7
,y8.val6 as soc8
from
(
select * 
from
DCWLW.dbo.newbox_b002
where nbox_b002_id in 
(select MAX(nbox_b002_id) from DCWLW.dbo.newbox_b002 group by device_code)
)x
left join DCWLW.dbo.device_date y1
on x.door1_bat_code=y1.barcode
left join DCWLW.dbo.device_date y2
on x.door2_bat_code=y2.barcode
left join DCWLW.dbo.device_date y3
on x.door3_bat_code=y3.barcode
left join DCWLW.dbo.device_date y4
on x.door4_bat_code=y4.barcode
left join DCWLW.dbo.device_date y5
on x.door5_bat_code=y5.barcode
left join DCWLW.dbo.device_date y6
on x.door6_bat_code=y6.barcode
left join DCWLW.dbo.device_date y7
on x.door7_bat_code=y7.barcode
left join DCWLW.dbo.device_date y8
on x.door8_bat_code=y8.barcode

以上的速度稍慢，不知有没有效率更高的方法