表A,B,C中都有字段：Name，学号
问题：当A中Name不为空时，取A中的Name
当B中Name不为空时，取B中Name
其他情况去C中Name
Name优先度：A>B>C
请教大侠这个SQL怎么写 ？？？？谢谢！
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- SQL code
select isnull(isnull(a.name,b,name),c.name) as name ,a.学号from a left join b on a.学号 = b.学号left join c on a.学号 = c.学号
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- SQL code
select COALESCE(a.Name,b.Name,c.Name) as NameCOALESCE(a.学号,b.学号,c.学号) as 学号from a full join b on a.Name=b.Namefull join c on c.Name=a.Name
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case when
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- SQL code
select case when a.name is not null then a.name else case when b.name is not null then b.name else c.name end endfrom tb
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- SQL code
select name=COALESCE(a.Name,b.Name,c.Name),a.学号from a left join b on a.学号 = b.学号left join c on a.学号 = c.学号