有一张表test如下：
create table test ( id int identity(1,1) primary key, num int )
插入数据：
insert into test( num) values (1); insert into test( num) values (2); insert into test( num) values (8); insert into test( num) values (15); insert into test( num) values (12); insert into test( num) values (13); insert into test( num) values (14); insert into test( num) values (16); insert into test( num) values (17); insert into test( num) values (5); insert into test( num) values (6); insert into test( num) values (7); insert into test( num) values (16); insert into test( num) values (18); insert into test( num) values (9); insert into test( num) values (10); insert into test( num) values (11); insert into test( num) values (12); insert into test( num) values (19); insert into test( num) values (20); insert into test( num) values (3); insert into test( num) values (4); insert into test( num) values (19); insert into test( num) values (20); insert into test( num) values (17); insert into test( num) values (18);