Getting the missing period through mmysql query or procedure..? - mysql

Question

I have a table customer_order as follows
mysql> select * from customer_order;
+---------+---------+-----------+------------------+----------------+
| cust_id | orderno | region_cd | order_start_date |order_del_date |
+---------+---------+-----------+------------------+----------------+
| CU_082 | ONO_001 | reg1 | 2012-04-25 | 2012-08-25 |
| CU_082 | ONO_002 | reg1 | 2012-04-28 | 2012-11-28 |
| CU_083 | ONO_002 | reg2 | 2012-04-28 | 2012-11-28 |
| CU_082 | ONO_003 | reg1 | 2012-04-25 | 2012-08-25 |
| CU_084 | ONO_004 | reg4 | 2012-04-25 | 2012-10-25 |
I need a table like this...which i get....as follows
mysql> select order_start_date,order_del_date,orderno,cust_id from customer_order wh
ere order_start_date >= '2012-04-25' AND order_del_date <='2012-12-28' and cust_i
d IN ('36082','36088') order by cust_id ;
+------------------+----------------+---------+---------+
| order_start_date | order_del_date | pid | emp_id |
+------------------+----------------+---------+---------+
| 2012-04-25 | 2012-05-25 | ONO_001 | CU_082 |
| 2012-08-22 | 2012-12-28 | ONO_004 | CU_082 |
| 2012-06-22 | 2012-08-28 | ONO_003 | CU_082 |
| 2012-05-27 | 2012-06-25 | ONO_002 | CU_082 |
| 2012-04-25 | 2012-05-25 | ONO_001 | CU_082 |
| 2012-05-27 | 2012-06-25 | ONO_001 | CU_082 |
| 2012-04-30 | 2012-06-25 | ONO_001 | CU_088 |
| 2012-06-28 | 2012-07-15 | ONO_002 | CU_088 |
| 2012-07-28 | 2012-08-25 | ONO_003 | CU_088 |
| 2012-07-16 | 2012-09-25 | ONO_004 | CU_088 |
+------------------+----------------+---------+---------+
now i need to query on this table ...
to get
for each customer here we get data for the period from wat date to wat date his order processing details in the above table..
now for each customer i shld find the period for which thr is no order processing...
eg cust_id =CU_088
he has his order processed from 30 apr to 25 june
den from 28th june to 15 july
(here thr is a diff that is thr is no order taken or any processing done from 26th to 27th june..this is wat is the required result)
**one more imp consideration is...
in the next entry we find thr is a order process from 28th july to 25th aug
w.r.t previous entry i.e, 28th june to 15july we find that for this customer thr is no order taken or processed from 16th to 27th july..
but with the last entry tat is 16th july to 25th sept he has an order with different order_no thrfore the gap 16th july to 27th july is filled here so this kind of a condition also needs to be checked...
I need to get the output as something like this..
+------------------+----------------+---------+---------+
| order_start_date | order_del_date | pid | emp_id |
+------------------+----------------+---------+---------+
| 2012-06-26 | 2012-06-27 | ONO_001 | CU_088 |
+------------------+----------------+---------+---------+
that is either the query or procedure which is more efficient should give me the period wer in thr was no action done for customer...
help me write the query which does the all the above things.
I m new to db queries..so please help me out..

Answer 1

To fetch every 'gap' between orders, you can use a self-join:
SELECT o1.cust_id,
o1.order_del_date + INTERVAL 1 DAY AS gap_begin,
MIN(o2.order_start_date) - INTERVAL 1 DAY AS gap_end
FROM customer_order o1
JOIN customer_order o2 ON o1.cust_id = o2.cust_id
AND o1.order_del_date <= o2.order_start_date
GROUP BY o1.cust_id, o1.order_del_date
HAVING gap_begin < gap_end