Postgres query how to club date and time if time is not null - postgresql

Question

with data as(SELECT c."id",c."accountId",c."name",c."campaignType",c."status",
(CASE WHEN cb."executionDetails"->>'initiatedAt' IS NULL THEN csr."startDate"
ELSE cast(cb."executionDetails"->>'initiatedAt' as TIMESTAMP)
END) as "startDate",
CASE WHEN cb."executionDetails"->>'initiatedAt' IS NOT NULL THEN NULL
ELSE csr."timeSlot"->>'type' END as "timeSlotType",
(CASE WHEN cb."executionDetails"->>'initiatedAt' IS not NULL THEN Null ELSE
-- CASE WHEN csr."timeSlotType"->>'startTime' IS NULL THEN NULL
CASE WHEN csr."timeSlot"->>'type'='MORNING' THEN '07:00'
WHEN csr."timeSlot"->>'type'='AFTERNOON' THEN '12:00'
WHEN csr."timeSlot"->>'type'='EVENING' THEN '17:00'
WHEN csr."timeSlot"->>'type'='CUSTOM' THEN (csr."timeSlot"->>'startTime')::json->>'hour'||':'||((csr."timeSlot"->>'startTime')::json->>'minute')
ELSE csr."timeSlot"->>'startTime' END END )::TIME as "startTime",
split_part(cb."batchRunId", '-',6)::decimal as batchNumber,
'CAMPAIGN' as type
FROM "Campaigns" c
LEFT JOIN "CampaignScheduleRequests" csr
ON c."id"=csr."campaignId"
LEFT JOIN "CampaignBatches" cb
ON csr."id"=cb."requestId")
SELECT * FROM data as d
WHERE d."status" IN ('ACTIVATED')
OUTPUT of the above query
Required o/p
Start time column should be concatenation of start date and startTime

Answer 1

with data as(
SELECT c."id",
c."accountId",
c."name",
c."campaignType",
c."status",
coalesce((cb."executionDetails"->>'initiatedAt')::timestamp,
csr."startDate")
) as "startDate",
CASE WHEN cb."executionDetails" ? 'initiatedAt' THEN NULL
ELSE csr."timeSlot"->>'type'
END as "timeSlotType",
(CASE WHEN cb."executionDetails" ? 'initiatedAt' THEN NULL
ELSE CASE csr."timeSlot"->>'type'
WHEN 'MORNING' THEN '07:00'
WHEN 'AFTERNOON' THEN '12:00'
WHEN 'EVENING' THEN '17:00'
WHEN 'CUSTOM' THEN (csr."timeSlot"->'startTime')->>'hour'
||':'
||(csr."timeSlot"->'startTime')->>'minute'
ELSE csr."timeSlot"->>'startTime' --invalid format could cause problems with ::time
END
END )::TIME as "startTime",
split_part(cb."batchRunId", '-',6)::decimal as batchNumber,
'CAMPAIGN' as type
FROM "Campaigns" c
LEFT JOIN "CampaignScheduleRequests" csr ON c."id"=csr."campaignId"
LEFT JOIN "CampaignBatches" cb ON csr."id"=cb."requestId"
WHERE c."status" IN ('ACTIVATED')
)
SELECT *,
"startDate"+coalesce("startTime",'00:00'::time) as "newStartTimestamp"
FROM data;
Use coalesce() to shorten the null replacements:
CASE WHEN cb."executionDetails"->>'initiatedAt' IS NULL
THEN csr."startDate"
ELSE cast(cb."executionDetails"->>'initiatedAt' as TIMESTAMP)
END
is the same as
coalesce((cb."executionDetails"->>'initiatedAt')::timestamp, csr."startDate")
In CASE you can do a single expression evaluation:
CASE expression
WHEN value1 THEN...
WHEN value2 THEN...
instead of a series of checks
CASE
WHEN expression=value1 THEN...
WHEN expression=value2 THEN...
Instead of casting back to json after using the ->> operator that gives you text: (jsonb->>'key1')::json->>'key2', you can just use -> to keep json output the first time.
? operator lets you check the presence of a key json?'key1' without having to check for null in an attempted read json->>'key1' is null.
You can add time to date or timestamp directly, the same how you'd add an interval. And to avoid nullifying your intitiatedAt-based startDate when adding a null-valued startTime, you can use coalesce() again - which I think was your main question.