Oracle--SQL技巧之一，查询连续的记录

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)