MySql中把一个字段替换成另一个字段

select case team

when 1 then '甲'

when 2 then ' 乙'

when 3 then '丙'

when 4 then ‘丁'

end as teamalias from 表

update b set bc1 = ( select ac1 from a where a.aid = b.bid)

where exists (select 1 from ac1 where a.aid = b.bid)

update B表 t1 inner join A表 t2 on t1.attr_value=t2.color_id

set t1.color_name=t2.color_name

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