Adding a number to a datetime to get new date SQL Server - sql

Question

I am trying to get the query below to assign a number value to the column 'DESIRED TRANSIT TIME' based on the value in that column - 10 if it starts with A and 5 if it starts with C. From there I want to add that number to REVISED_EX_FACTORY to get a new ex factory. I have never attempted this and using the query below I get the result which is the date plus the text 'DESIRED TRANSIT TIME' - which kind of makes sense since it is a string. How can I get the value in the column instead of the textual name of the column in line 20? I was told converting the datetime values to get rid of the time component was a good way to go.
The ideal result would be to either add 5 or 10 days to the date depending the value in 'DESIRED TRANSIT TIME'
SQL:
USE PDX_SAP_USER
GO
SELECT E.team_member_name [EMPLOYEE],
K.business_segment_desc [BUSINESS SEGMENT],
G.order_status [GPS ORDER STATUS],
H.po_type [PO TYPE],
G.order_no [GPS ORDER NO],
I.po_number [SAP PO NUMBER],
I.shipping_instruct [SAP SHIP MODE],
G.shipping_type [GPS SHIP MODE],
CASE
WHEN I.shipping_instruct LIKE 'A%'
THEN '10'
WHEN I.shipping_instruct LIKE 'C%'
THEN '5'
END [DESIRED TRANSIT TIME],
CONVERT(VARCHAR(12),I.revised_ex_factory,101) [LAST CONFIRMED DATE ],
CONVERT(VARCHAR(12),I.revised_ex_factory,101) + 'DESIRED TRANSIT TIME' AS 'PROPOSED ETA',
CONVERT(VARCHAR(12),S.po_estimated_deliv_date,101) [CURRENT DELIV DATE],
-- 'days_diff'
I.material [MATERIAL],
M.description [DESCRIPTION],
I.stock_category [STOCK CATEGORY],
I.po_ordered_quantity [PO ORDERED QUANTITY],
I.po_recvd_quantity [PO RECVD QUANTITY],
I.po_balance_quantity [PO BALANCE QUANTITY],
I.po_intransit_quantity [PO INTRANSIT QUANTITY],
I.plant_code [PLANT],
I.direct_ship_code [DS CODE],
I.comment [COMMENT]
FROM (SELECT order_no,
order_status,
shipping_type
FROM asagdwpdx_prod.dbo.SimoxOrder1
UNION ALL
SELECT order_no,
order_status,
shipping_type
FROM asagdwpdx_prod.dbo.SimoxOrder2
UNION ALL
SELECT order_no,
order_status,
shipping_type
FROM asagdwpdx_prod.dbo.SimoxOrder3) G
JOIN pdx_sap_user..vw_po_header H ON G.order_no = H.ahag_number
JOIN pdx_sap_user..vw_po_item I ON H.po_number = I.po_number
JOIN pdx_sap_user..vw_po_size S ON I.po_number = S.po_number
AND I.po_item_number = S.po_item_number
JOIN pdx_sap_user..vw_mm_material M ON I.material = M.material
JOIN pdx_sap_user..vw_kd_business_segment K ON M.business_segment_code = K.business_segment_code
JOIN adi_user_maintained..scm_po_employee_name E ON I.po_number = E.po_number
WHERE I.po_balance_quantity > 0
AND I.del_indicator NOT IN ('L','S')
AND H.PO_TYPE NOT IN ('01','UB')
AND I.shipping_instruct IN ('A1','A2','A5','C1','C2','C3')
SAMPLE RESULT:
04/30/2016DESIRED TRANSIT TIME

Answer 1

So you have two options. The first is to duplicate the CASE statement you have a second time, and concatenate that with the date. That's probably the most straight forward, although you will end up duplicating that code. It's a small duplication, but one none the less. If that bothers you, or you need to use it elsewhere in your query as well, you will need to wrap the whole thing in a subquery so you can reference the case statement as though it were a distinct column. e.g.
select
...
DesiredTransitTime =
case
when I.shipping_instruct LIKE 'A%'
then '10'
when I.shipping_instruct LIKE 'C%'
then '5'
end,
ProposedETA = convert(varchar(12),I.revised_ex_factory,101) +
case
when I.shipping_instruct LIKE 'A%'
then '10'
when I.shipping_instruct LIKE 'C%'
then '5'
end
...
or
select
[DESIRED TRANSIT TIME],
[PROPOSED ETA = StringDate + [DESIRED TRANSIT TIME]
...
from
(
select
StringDate = convert(varchar(12), I.revised_ex_factory,101) ,
[DESIRED TRANSIT TIME] =
case
when I.shipping_instruct LIKE 'A%'
then '10'
when I.shipping_instruct LIKE 'C%'
then '5'
end,
...
) a