select top 10 studentname from t1,t2 order by f DESC
SELECT top 10 T3.studentName,T3.f from (SELECT studentName,f FROM T1 UNION SELECT studentName,f FROM T2) as T3 order by f DESC
SELECT top 10 T3.studentName,T3.f from (SELECT studentName,f FROM T1 UNION SELECT studentName,f FROM T2) T3 order by T3.f DESC第二行as不应该有吧?关于union all:缺省地,UNION 的结果不包含任何重复的行,除非声明了 ALL 子句,楼上的?难道有同班同名同分?
from (SELECT studentName,f FROM T1 UNION SELECT studentName,f FROM T2) as T3
order by f DESC
from (SELECT studentName,f FROM T1 UNION SELECT studentName,f FROM T2) T3
order by T3.f DESC第二行as不应该有吧?关于union all:缺省地,UNION 的结果不包含任何重复的行,除非声明了 ALL 子句,楼上的?难道有同班同名同分?
一般再写SQL语句的时候不要用多表连接比如是from 表名1,表名2,...
而是用嵌套查询,效率要高出很多.