case statement with in case statement - oracle

Question

I am not sure what kind of statement I need in order for what i need to do. I would like to add a case statement after the case statement i currently have. Bellow is the case statement.
CASE
WHEN LOCOFF.EXT_SRV_POLYGON IN ('BOF', 'CDA', 'COL', 'DAC', 'GOS', 'KEL', 'KLF', 'LAG', 'LEC', 'MED', 'PUM', 'RIT', 'ROS', 'SAN', 'SPO')
THEN 'GAS'
WHEN LOCOFF.EXT_SRV_POLYGON IN ('CDC', 'COC', 'DAV', 'DPC', 'GRC', 'KEC', 'LCC', 'OTC', 'PAC', 'SAC', 'SPC')
THEN 'ELECTRIC'
ELSE 'MISSING'
END AS TYPE,
I would like to say if EXT_Distworktype is GC or GT and the TYPE is ELECTRIC,
GIVE ME TYPE THAT SAYS WRONG POLYGON OR IF THE EXT_DISTWORKTYPE is EC, ES, or ET and Type is GAS then give me a TYPE that say WRONG POLYGON.
here is my full query:
SELECT WO.WONUM AS "Work Order",
WO.LOCATION AS "Location",
WO.STATUS AS "Status",
WO.DESCRIPTION,
WO.ACTFINISH AS "Actual Finish",
WO.PARENT AS "Parent WO",
WO.WORKTYPE AS "Work Type",
CASE
WHEN WO.REPORTDATE IS NULL
THEN TO_DATE('29-JAN-15 00:00:00', 'DD-MON-YY HH24:MI:SS')
ELSE WO.REPORTDATE
END AS "Reported Date",
WO.SITEID AS "Site",
CASE
WHEN WO.ACTFINISH IS NULL
THEN GREATEST(TRUNC(TO_DATE(SysDate, 'DD-MON-YY HH24:MI:SS') - TO_DATE(WO.REPORTDATE, 'DD-MON-YY HH24:MI:SS'), 6), 0)
WHEN WO.STATUS NOT IN ('COMP')
THEN GREATEST(TRUNC(TO_DATE(SysDate, 'DD-MON-YY HH24:MI:SS') - TO_DATE(WO.REPORTDATE, 'DD-MON-YY HH24:MI:SS'), 6), 0)
WHEN WO.STATUS IN ('COMP')
THEN GREATEST(TRUNC(TO_DATE(WO.ACTFINISH, 'DD-MON-YY HH24:MI:SS') - TO_DATE(WO.REPORTDATE, 'DD-MON-YY HH24:MI:SS'), 6), 0)
END AS "Age",
WO.EXT_DISTWORKTYPE,
LOCOFF.EXT_OFFICE,
CASE
WHEN LOCOFF.EXT_SRV_POLYGON IN ('BOF', 'CDA', 'COL', 'DAC', 'GOS', 'KEL', 'KLF', 'LAG', 'LEC', 'MED', 'PUM', 'RIT', 'ROS', 'SAN', 'SPO')
THEN 'GAS'
WHEN LOCOFF.EXT_SRV_POLYGON IN ('CDC', 'COC', 'DAV', 'DPC', 'GRC', 'KEC', 'LCC', 'OTC', 'PAC', 'SAC', 'SPC')
THEN 'ELECTRIC'
ELSE 'MISSING'
END AS TYPE,
LOCOFF.EXT_STATECODE,
WO.OWNERGROUP,
WO.EXT_JOBCODE
FROM LOCATIONS LOCOFF
RIGHT JOIN WORKORDER WO
ON WO.LOCATION = LOCOFF.LOCATION
WHERE WO.STATUS NOT IN ('CLOSE', 'WAIV', 'CAN', 'REJ', 'REVOKED')
AND LOCOFF.SITEID = 'OPS'
AND WO.EXT_JOBCODE NOT LIKE 'A%' AND WO.E`enter code here`XT_JOBCODE NOT LIKE 'B%'
AND WO.EXT_JOBCODE NOT IN ('K008','K009','I006','I007','I008');

Answer 1

You can nest case expressions if you only want to modify the existing column value (rather than adding a separate column with the 'wrong polygon' message):
CASE
WHEN LOCOFF.EXT_SRV_POLYGON IN ('BOF', 'CDA', 'COL', 'DAC', 'GOS', 'KEL', 'KLF', 'LAG', 'LEC', 'MED', 'PUM', 'RIT', 'ROS', 'SAN', 'SPO')
THEN
CASE
WHEN WO.EXT_DISTWORKTYPE IN ('EC', 'ES', 'ET')
THEN 'WRONG POLYGON'
ELSE 'GAS'
END
WHEN LOCOFF.EXT_SRV_POLYGON IN ('CDC', 'COC', 'DAV', 'DPC', 'GRC', 'KEC', 'LCC', 'OTC', 'PAC', 'SAC', 'SPC')
THEN
CASE
WHEN WO.EXT_DISTWORKTYPE IN ('GC', 'GT')
THEN 'WRONG POLYGON'
ELSE 'ELECTRIC'
END
ELSE 'MISSING'
END AS TYPE,
Quick SQL Fiddle demos with the same made-up data; your original case and this nested case, which gives:
EXT EX TYPE
--- -- -------------
BOF GC GAS
CDA GT GAS
SPO ES WRONG POLYGON
CDC EC ELECTRIC
COC ET ELECTRIC
SPC GC WRONG POLYGON
This is a bit simpler than trying to do a second step that interprets the TYPE value, because you can't refer to a column alias in the same level of query; you would need to make your existing query into an inline view.

Answer 2

Will an extra case not do it?
CASE
WHEN WO.EXT_DISTWORKTYPE IN ('GC', 'GT')
AND LOCOFF.EXT_SRV_POLYGON IN ('CDC', 'COC', 'DAV', 'DPC', 'GRC', 'KEC', 'LCC', 'OTC', 'PAC', 'SAC', 'SPC') --electronic
THEN 'WRONG POLYGON'
CASE
WHEN WO.EXT_DISTWORKTYPE IN ('EC', 'ES', 'ET' )
AND LOCOFF.EXT_SRV_POLYGON IN ('BOF', 'CDA', 'COL', 'DAC', 'GOS', 'KEL', 'KLF', 'LAG', 'LEC', 'MED', 'PUM', 'RIT', 'ROS', 'SAN', 'SPO') --gas
THEN 'WRONG POLYGON'
ELSE 'MSSING'
END AS YOURANSWER,
You could do an case within a case
CASE
WHEN (TRUE) THEN
CASE WHEN (true) THEN 'a' ELSE 'b' END
ELSE
'A'
END