group by picking columns with null value - mysql - mysql

Question

I am working on a query and want to group the rows and return groupped data but my query is not working as expected.
my query-
select item, branch, packunit,packlevel,dealqty,PromotionFlag,PromotionID, PromotionEndDate, cnc,delivery, volumedeal, standard_price_scheme,
deliv_price_scheme
from
(
SELECT
`item` AS `item`,
`branch` AS `branch`,
`PackUnit` AS `PackUnit`,
`PackLevel` AS `PackLevel`,
`DealQty` AS `DealQty`,
`PromotionFlag` AS `PromotionFlag`,
`PromotionID` AS `PromotionID`,
`PromotionEndDate` AS `PromotionEndDate`,
SUM(`cnc`) AS `cnc`,
SUM(`delivery`) AS `delivery`,
SUM(`volumedeal`) AS `volumedeal`,
`standard_price_scheme` AS `standard_price_scheme`,
`deliv_price_scheme` AS `deliv_price_scheme`
FROM
(
SELECT DISTINCT
`Pricing_Today`.`item` AS `item`,
`Pricing_Today`.`branch` AS `branch`,
`Pricing_Today`.`price_scheme` AS `price_scheme`,
`Pricing_Today`.`PackUnit` AS `PackUnit`,
`Pricing_Today`.`PackLevel` AS `PackLevel`,
`Pricing_Today`.`DealQty` AS `DealQty`,
`Pricing_Today`.`PromotionFlag` AS `PromotionFlag`,
`Pricing_Today`.`PromotionID` AS `PromotionID`,
`Pricing_Today`.`PromotionEndDate` AS `PromotionEndDate`,
(CASE
WHEN (`Pricing_Today`.`PriceType` = 'C&C') THEN `Pricing_Today`.`Sell`
END) AS `cnc`,
(CASE
WHEN (`Pricing_Today`.`PriceType` = 'Delivery') THEN `Pricing_Today`.`Sell`
END) AS `delivery`,
(CASE
WHEN (`Pricing_Today`.`PriceType` = 'Volume Deal') THEN `Pricing_Today`.`Sell`
END) AS `volumedeal`,
(CASE
WHEN (`Pricing_Today`.`PriceType` = 'C&C') THEN `Pricing_Today`.`price_scheme`
END) AS `standard_price_scheme`,
(CASE
WHEN
((`Pricing_Today`.`PriceType` = 'Delivery')
OR (`Pricing_Today`.`PriceType` = 'Volume Deal'))
THEN
`Pricing_Today`.`price_scheme`
END) AS `deliv_price_scheme`
FROM
`Pricing_Today`
where item = 78867
and branch = 0
GROUP BY `Pricing_Today`.`item` , `Pricing_Today`.`PackUnit` , `Pricing_Today`.`PriceType`,`standard_price_scheme`,`deliv_price_scheme`
) as a
GROUP BY branch,`item` , `PackUnit`,`standard_price_scheme`,`deliv_price_scheme`
) as a
-- group by item, packunit
which returns -
BUT, when I group by item, pack I get this -
for cnc its showing null values. How do I eliminate null values and get the numbers?
Thanks in advance

Answer 1

You need to take aggregates of the CASE expressions:
SELECT
p.item,
p.branch,
p.price_scheme,
p.PackUnit,
p.PackLevel,
p.DealQty,
p.PromotionFlag,
p.PromotionID,
p.PromotionEndDate,
MAX(CASE WHEN p.PriceType = 'C&C' THEN p.Sell END) AS cnc,
MAX(CASE WHEN p.PriceType = 'Delivery' THEN p.Sell END) AS delivery,
MAX(CASE WHEN p.PriceType = 'Volume Deal' THEN p.Sell END) AS volumedeal,
MAX(CASE WHEN p.PriceType = 'C&C' THEN p.price_scheme END) AS standard_price_scheme,
MAX(CASE WHEN p.PriceType = 'Delivery' OR p.PriceType = 'Volume Deal'
THEN p.price_scheme END) AS deliv_price_scheme
FROM
Pricing_Today p
WHERE
item = 78867 AND branch = 0
GROUP BY
p.item,
p.branch,
p.price_scheme,
p.PackUnit,
p.PackLevel,
p.DealQty,
p.PromotionFlag,
p.PromotionID,
p.PromotionEndDate;
This is just a standard pivot query. The idea behind taking the MAX of a CASE expression is that if a given group of records has a single non NULL value, then MAX would correctly extract it. This works because MAX ignores NULL values.
Note that I removed the backticks from your query, none of which were necessary. I try to avoid using backticks unless they are really needed, because it makes the query harder to read.