select AA.name,

   A.语文成绩,

   B.数学成绩

from

(select distinct name from A

union 

select distinct name from B) AA

left join A

on A.name=AA.name

left join B

on B.name=AA.name

select A.语文成绩，B.数学成绩，A.name from A left join  B on A.name=B.name

select a.name,a.语文成绩,b.数学成绩 from A a FULL JOIN B b ON a.name = b.name

--第一种

select

name,

sum(ywcj) as ywcj,

sum(sxcj) as sxcj

from

(select name,[语文成绩] as ywcj,0 as sxcj from A

union all

select name,0 as ywcj,[数学成绩] as sxcj from B) as x

group by name

--第二种

select

case when A.name is not null then A.name else B.name end as name,

isnull(A.[语文成绩],0) as ywcj,

isnull(B.[数学成绩],0) as sxcj

from A

full join B

on A.name = B.name