下面为您介绍的SQL语句用于实现DB2分类取前N个记录，如果您遇到过DB2分类取前N个记录的问题，不妨一看 。
有一个表t1，结构如下：
类别编号 说明 排序
a aa 1
a aa2 4
a aa3 6
b bb 1
b bb2 3
b bb3 5
c cc 1
c cc2 5
c cc3 7
需要查询出来的结果是每个类别的头2条记录，按排序进行排序，结果如下：
类别编号 说明 排序
a aa 1
a aa2 4
b bb 1
b bb2 3
c cc 1
c cc2 5
create table t1(
yTypeCode varchar(10),
yMemo varchar(10),
yOrder int
)
insert into t1(yTypeCode,yMemo,yOrder) values( a , aa ,1);
insert into t1(yTypeCode,yMemo,yOrder) values( a , aa2 ,4);
insert into t1(yTypeCode,yMemo,yOrder) values( a , aa3 ,6);
insert into t1(yTypeCode,yMemo,yOrder) values( b , bb ,1);
insert into t1(yTypeCode,yMemo,yOrder) values( b , bb2 ,2);
insert into t1(yTypeCode,yMemo,yOrder) values( b , bb3 ,3);
insert into t1(yTypeCode,yMemo,yOrder) values( c , cc ,1);
insert into t1(yTypeCode,yMemo,yOrder) values( c , cc2 ,5);
insert into t1(yTypeCode,yMemo,yOrder) values( c , cc3 ,8)
实现;
SELECT * FROM t1 t
WHERE (SELECT count(*) FROM t1 WHERE yTypeCode=t.yTypeCode AND yOrder
