select b.姓名,
(select a.value from a where a.key=b.性别) as 性别,
(select a.value from a where a.key=b.所在城市) as 所在城市,
(select a.value from a where a.key=b.政治面貌) as 政治面貌
from b
SELECT T1.姓名,T2.value[性别],T3.value[所在城市],T4.value[政治面貌]
FROM b表 T1
LEFT JOIN a表 T2 ON T1.性别=T2.[key]
LEFT JOIN a表 T3 ON T1.所在城市=T3.[key]
LEFT JOIN a表 T4 ON T1.政治面貌=T4.[key]