oracle—SQL技巧之(一)连续记录查询sql案例测试

需求说明：
需要查询出某个客户某一年那些天是有连续办理过业务

实现sql如下：
创建表：

create table test_num
(tyear number,
tdate date);

测试数据：
insert into test_num
select 2014,trunc(sysdate)-1 from dual union all
select 2014,trunc(sysdate)-002 from dual union all
select 2014,trunc(sysdate)-003 from dual union all
select 2014,trunc(sysdate)-004 from dual union all
select 2014,trunc(sysdate)-005 from dual union all
select 2014,trunc(sysdate)-007 from dual union all
select 2014,trunc(sysdate)-008 from dual union all
select 2014,trunc(sysdate)-009 from dual union all
select 2013,trunc(sysdate)-120 from dual union all
select 2013,trunc(sysdate)-121 from dual union all
select 2013,trunc(sysdate)-122 from dual union all
select 2013,trunc(sysdate)-124 from dual union all
select 2013,trunc(sysdate)-125 from dual union all
select 2013,trunc(sysdate)-127 from dual union all
select 2015,trunc(sysdate)-099 from dual union all
select 2015,trunc(sysdate)-100 from dual union all
select 2015,trunc(sysdate)-101 from dual union all
select 2015,trunc(sysdate)-102 from dual union all
select 2015,trunc(sysdate)-104 from dual union all
select 2015,trunc(sysdate)-105 from dual;

写sql:

select tyear, min(tdate) as startdate, max(tdate), count(tyear) as endnum
from (select a.*, a.tdate - rownum as gnum
from (select * from test_num order by tyear, tdate) a)
group by tyear, gnum
order by tyear, min(tdate)