Netezza: Show dates even if 0 data for that day - netezza

Question

I have this query through an odbc connection in excel for a refreshable report with data for every 4 weeks. I need to show the dates in each of the 4 weeks even if there is no data for that day because this data is then linked to a Graph. Is there a way to do this?
thanks.
Select b.INV_DT, sum( a.ORD_QTY) as Ordered, sum( a.SHIPPED_QTY) as Shipped
from fct_dly_invoice_detail a, fct_dly_invoice_header b, dim_invoice_customer c
where a.INV_HDR_SK = b.INV_HDR_SK
and b.DIM_INV_CUST_SK = c.DIM_INV_CUST_SK
and a.SRC_SYS_CD = 'ABC'
and a.NDC_NBR is not null
**and b.inv_dt between CURRENT_DATE - 16 and CURRENT_DATE**
and b.store_nbr in (2851, 2963, 3249, 3385, 3447, 3591, 3727, 4065, 4102, 4289, 4376, 4793, 5209, 5266, 5312, 5453, 5569, 5575, 5892, 6534, 6571, 7110, 9057, 9262, 9652, 9742, 10373, 12392, 12739, 13870
)
group by 1

Answer 1

The general purpose solution to this is to create a date dimension table, and then perform an outer join to that date dimension table on the INV_DT column.
There are tons of good resources you can search for on creating a good date dimension table, so I'll just create a quick and dirty (and trivial) example here. I highly recommend some research in that area if you'll be doing a lot of BI/reporting.
If our table we want to report from looks like this:
Table "TABLEZ"
Attribute | Type | Modifier | Default Value
-----------+--------+----------+---------------
AMOUNT | BIGINT | |
INV_DT | DATE | |
Distributed on random: (round-robin)
select * from tablez order by inv_dt
AMOUNT | INV_DT
--------+------------
1 | 2015-04-04
1 | 2015-04-04
1 | 2015-04-06
1 | 2015-04-06
(4 rows)
and our report looks like this:
SELECT inv_dt,
SUM(amount)
FROM tablez
WHERE inv_dt BETWEEN CURRENT_DATE - 5 AND CURRENT_DATE
GROUP BY inv_dt;
INV_DT | SUM
------------+-----
2015-04-04 | 2
2015-04-06 | 2
(2 rows)
We can create a date dimension table that contains a row for every date (or ate last 1024 days in the past and 1024 days in the future using the _v_vector_idx view in this example).
create table date_dim (date_dt date);
insert into date_dim select current_date - idx from _v_vector_idx;
insert into date_dim select current_date + idx +1 from _v_vector_idx;
Then our query would look like this:
SELECT d.date_dt,
SUM(amount)
FROM tablez a
RIGHT OUTER JOIN date_dim d
ON a.inv_dt = d.date_dt
WHERE d.date_dt BETWEEN CURRENT_DATE -5 AND CURRENT_DATE
GROUP BY d.date_dt;
DATE_DT | SUM
------------+-----
2015-04-01 |
2015-04-02 |
2015-04-03 |
2015-04-04 | 2
2015-04-05 |
2015-04-06 | 2
(6 rows)
If you actually needed a zero value instead of a NULL for the days where you had no data, you could use a COALESCE or NVL like this:
SELECT d.date_dt,
COALESCE(SUM(amount),0)
FROM tablez a
RIGHT OUTER JOIN date_dim d
ON a.inv_dt = d.date_dt
WHERE d.date_dt BETWEEN CURRENT_DATE -5 AND CURRENT_DATE
GROUP BY d.date_dt;
DATE_DT | COALESCE
------------+----------
2015-04-01 | 0
2015-04-02 | 0
2015-04-03 | 0
2015-04-04 | 2
2015-04-05 | 0
2015-04-06 | 2
(6 rows)

Answer 2

I agree with #ScottMcG that you need to get the list of dates. However if you are in a situation where you aren't allowed to create a table. You can simplify things. All you need is a table that has at least 28 rows. Using your example, this should work.
select date_list.dt_nm, nvl(results.Ordered,0) as Ordered, nvl(results.Shipped,0) as Shipped
from
(select row_number() over(order by sub.arb_nbr)+ (current_date -28) as dt_nm
from (select rowid as arb_nbr
from fct_dly_invoice_detail b
limit 28) sub ) date_list left outer join
( Select b.INV_DT, sum( a.ORD_QTY) as Ordered, sum( a.SHIPPED_QTY) as Shipped
from fct_dly_invoice_detail a inner join
fct_dly_invoice_header b
on a.INV_HDR_SK = b.INV_HDR_SK
and a.SRC_SYS_CD = 'ABC'
and a.NDC_NBR is not null
**and b.inv_dt between CURRENT_DATE - 16 and CURRENT_DATE**
and b.store_nbr in (2851, 2963, 3249, 3385, 3447, 3591, 3727, 4065, 4102, 4289, 4376, 4793, 5209, 5266, 5312, 5453, 5569, 5575, 5892, 6534, 6571, 7110, 9057, 9262, 9652, 9742, 10373, 12392, 12739, 13870)
inner join
dim_invoice_customer c
on b.DIM_INV_CUST_SK = c.DIM_INV_CUST_SK
group by 1 ) results
on date_list.dt_nm = results.inv_dt