select a.* from test a where 1 > (select count(*) from test where name = a.name and val > a.val )sql语句,按name分组显示最大的val值的字段,不明白具体意思,

select a.* from test a where 1 > (select count(*) from test where name = a.name and val > a.val )sql语句,按name分组显示最大的val值的字段,不明白具体意思, select * from a union select * from b 能详细说下么 select * into b from a where 11 select count(*) as total from 'test' order by id desc 希望得到正解 select * from (select a.*,rownum aa from table a ) where aa=10 group by 和 distinct 的问题select a.partner as pcode, count(distinct(a.deviceid)) as count -- into num4 from test a where a.activationtime >= to_date('2011-4-17', 'yyyy-mm-dd') and a.activationtime < to_date( select *from A where A.a like '%1%'||'%' 关系代数 现有表test内有属性（t1,t2,t3）SQL语句：select *from test as A,test as Bwhere A.t1 = B.t3该语句写成关系代数表达式时,本人对 “自身连接时取别名” 感到困难感谢您的回答,我希望得到的是关 Please select a city or zipcode from the drop-down. Please select a plan from the options to the select * from book limit , insert into a select * from b 和select * into a from b 这两个语句是不是一样的? select id from (select id from pedigree group by number having count(name)>1)as a; 为啥用as a select c.*,d* from ( select 图号 from ( SELECT a.*,b.存货编码 FROM 未明图号 as a left OUTER JOIN 存select c.*,d* from ( select 图号 from (SELECT a.*,b.存货编码FROM 未明图号 as a left OUTER JOIN 存货档案 as bON a.图号=b.规 select from 表 和select from [表]有什么不同? select count(*) from 怎么使用 select count(1) from emp select * into dept2 from dept