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问题：
数据库中人表有三个属性，用户（编号，姓名，身高），查询出该身高排名第二的高度。
建表语句
create table users ( id int identity(1,1) primary key, name varchar(20), height float );
测试数据
insert into users(name,height) values(‘zhangsan‘,182); insert into users(name,height) values(‘李四‘,122); insert into users(name,height) values(‘张强‘,132); insert into users(name,height) values(‘王明‘,122); insert into users(name,height) values(‘姜明‘,182); insert into users(name,height) values(‘蒋克龙‘,182); insert into users(name,height) values(‘zhang‘,182); insert into users(name,height) values(‘安安‘,181); insert into users(name,height) values(‘健健‘,181); insert into users(name,height) values(‘明明‘,181); insert into users(name,height) values(‘小小‘,177); insert into users(name,height) values(‘旺旺‘,123); insert into users(name,height) values(‘卡纳‘,175); insert into users(name,height) values(‘文鑫‘,166); insert into users(name,height) values(‘健明‘,155); insert into users(name,height) values(‘拉拉‘,152); insert into users(name,height) values(‘青青‘,132); insert into users(name,height) values(‘乐乐‘,155); insert into users(name,height) values(‘KK‘,123); insert into users(name,height) values(‘FF‘,122); insert into users(name,height) values(‘Lily‘,152);
查询语句
1、查询出没有重复值的第二名，即假如最高的身高是182，有几个人同时身高是182，则查出身高小于182的的最高的身高值。
1>、方式1：
select MAX(height) from users where height < (select MAX(height) from users );
解析：先查询出最高的身高值，然后查询身高小于该值的最高身高。
2>、方式2：
select top 1 height from users where height not in (select MAX(height) from users) order by height desc;
解析：先查询出最高的身高，排除该身高，然后将数据进行排序（降序），查询出当前的第一条数据。
3>、方式3：
查询出可能与最高身高值相同的第二名，即假如身高最高是182，有几个人同时是182身高，第二名依然是182.
select top 1 * from (select top 2 height from users order by height desc) s order by height asc;
解析：将数据按照身高（降序）排列，查询出前面的两项，然后将这两项按照身高升序，查询第一项目。
http://www.cnblogs.com/0201zcr/p/4820706.html
Oracle版本：
--创建表 declare tableNum number; begin select count(1) into tableNum from user_tables t where t.TABLE_NAME = ‘USERS‘; dbms_output.put_line(‘Table Num:‘ || tableNum); if (tableNum = 0) then execute immediate ‘create table USERS( id number(10), name varchar2(20), height number(3), constraint USERS_ID_PK primary key (id))‘; else truncate table USERS; end if; select count(1) into tableNum from user_tables t where t.TABLE_NAME = ‘USERS‘; dbms_output.put_line(‘Table Num:‘ || tableNum); --insert into users (id,name, height) values (1,‘zhangsan‘, 182); end;
这个块中，在创建表结构后，不能直接insert，会报表不存在
输出结果：
要显示dbms_output.put_line的输入内容，需要在command或sqlplus中执行set serverout on;
Table Num:0 Table Num:1 PL/SQL procedure successfully completed
insert into users (id,name, height) values (1,‘zhangsan‘, 182); insert into users (id,name, height) values (2,‘李四‘, 122); insert into users (id,name, height) values (3,‘张强‘, 132); insert into users (id,name, height) values (4,‘王明‘, 122); insert into users (id,name, height) values (5,‘姜明‘, 182); insert into users (id,name, height) values (6,‘蒋克龙‘, 182); insert into users (id,name, height) values (7,‘zhang‘, 182); insert into users (id,name, height) values (8,‘安安‘, 181); insert into users (id,name, height) values (9,‘健健‘, 181); insert into users (id,name, height) values (10,‘明明‘, 181); insert into users (id,name, height) values (11,‘小小‘, 177); insert into users (id,name, height) values (12,‘旺旺‘, 123); insert into users (id,name, height) values (13,‘卡纳‘, 175); insert into users (id,name, height) values (14,‘文鑫‘, 166); insert into users (id,name, height) values (15,‘健明‘, 155); insert into users (id,name, height) values (16,‘拉拉‘, 152); insert into users (id,name, height) values (17,‘青青‘, 132); insert into users (id,name, height) values (18,‘乐乐‘, 155); insert into users (id,name, height) values (19,‘KK‘, 123); insert into users (id,name, height) values (20,‘FF‘, 122); insert into users (id,name, height) values (21,‘Lily‘, 152);
select max(j.height) from users j where j.height < (select max(s.height) from users s)
select g.height from (select j.height from users j where j.height not in (select MAX(j.height) from users j) order by j.height desc) g where /*rownum < 2*/ rownum = 1;
select g.height from (select t.height from (select j.height from users j where rownum < 3 order by j.height desc) t order by t.height asc) g where rownum < 2 /* rownum=1*/ ;
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原文地址：http://www.cnblogs.com/softidea/p/4821946.html
