I have 3 table, Documents
, SR
and events
In documents
I am saving all documents related to SR and Events.
And I want to show all documents in one page.
So I am using this select query
Select *
from documents d, SR s, Events e
where d.relationid = ( case d.documenttype when 'SR' the s.SRId else 'e.eventid end)
but it's not working.
My document
table structure is like this :
documentid int,
documenttype nvarchar(50),
relationid int,
document image,
docdate date
Can anyone please point me to my mistake ?
I want to select all documents with related info. means if its SR document than SR details should display otherwise Events. There is only 2 types of documents right now.
What should be my select query for this ?
You can join then using LEFT JOIN
,
SELECT d.*,
COALESCE(s.Col1, e.Col1) AS Col1,
COALESCE(s.Col2, e.Col2) AS Col2,
COALESCE(s.Col3, e.Col3) AS Col3,
COALESCE(s.Col4, e.Col4) AS Col4
FROM documents d
LEFT JOIN SR s
ON d.relationID = d.SRID
LEFT JOIN Events e
ON d.relationID = e.eventID
where Col1,...., Col4
are the columns of each table youw ant to be displayed based on documenttype
.
To further gain more knowledge about joins, kindly visit the link below:
The more safe version of the query above assuming that the same ID can contain on SR
and Events
table would be by using CASE()
SELECT d.*,
CASE WHEN d.documenttype = 'SR' THEN s.Col1 ELSE e.Col1 END) AS Col1,
CASE WHEN d.documenttype = 'SR' THEN s.Col2 ELSE e.Col2 END) AS Col2,
CASE WHEN d.documenttype = 'SR' THEN s.Col3 ELSE e.Col3 END) AS Col3,
CASE WHEN d.documenttype = 'SR' THEN s.Col4 ELSE e.Col4 END) AS Col4
FROM documents d
LEFT JOIN SR s
ON d.relationID = d.SRID
LEFT JOIN Events e
ON d.relationID = e.eventID
Something along these lines
SELECT
CASE WHEN SR.DocumentType = 'SR' THEN s.SRid ELSE e.eventId END AS Id
FROM documents d
LEFT JOIN SR s
ON s.SRId = d.relationId
LEFT JOIN Events e
ON e.EventId = d.relationId
This should work.
Select *
from documents d
left join SR s on d.relationid = d.SRId
left join Events e on d.relationid = e.eventid
where d.relationid = ( case when d.documenttype = 'SR' then s.SRId else e.eventid end)
You no need to write Where clause as you need all records
Below Query Works for sure
Select DocumentID,
DocumentType,
RelationID,
case when DocumentType = 'SR' then S.SRID else E.EventID end as Doc_DataID
From
Documents D
Left outer join SR S on D.RelationID = S.SRID
LEFT OUTER JOIN EVENTS E on E.EventiD = D.RelationID
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