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SQLite  Query needed

Posted on 2013-05-27
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Last Modified: 2013-05-27
I need to do a select from a table doing something like this:

select n.name from IDTONAME n, MANYCOLUMNS M where n.id=M.column1

Basically, the values in column1 of the MANYCOLUMNS table are used to find a name from the IDTONAME table.

This would work fine, I only wanted a single column in the result set, but I need several columns, each with the id in the M table used to find the name from the n table.

I tried this:

select (select n.name from IDTONAME n, MANYCOLUMNS M where n.id=M.column1),
          (select n.name from IDTONAME n, MANYCOLUMNS M where n.id=M.column2),

.....

but then even the first column is not correct---I get the same name for each record in the result set instead of the name associated with the id in the column.

Thanks,

Dave Thomas
0
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Question by:DaveThomasPilot
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8 Comments
 

Author Comment

by:DaveThomasPilot
ID: 39199900
Clarifying, I want a record in the return set for every record in MANYCOLUMNS.  The field values should correspond to the names in the IDTONAME table, as indexed by the values in the MANYCOLUMNS table.
0
 
LVL 25

Expert Comment

by:chaau
ID: 39199913
You need to use UNION

select n.name from IDTONAME n, MANYCOLUMNS M where n.id=M.column1
UNION ALL
select n.name from IDTONAME n, MANYCOLUMNS M where n.id=M.column2
UNION ALL
select n.name from IDTONAME n, MANYCOLUMNS M where n.id=M.column3
etc...

Open in new window


If you need to sort it as well, then add ID to the selection and sort by it

select n.name, n.ID from IDTONAME n, MANYCOLUMNS M where n.id=M.column1
UNION ALL
select n.name, n.ID from IDTONAME n, MANYCOLUMNS M where n.id=M.column2
UNION ALL
select n.name, n.ID from IDTONAME n, MANYCOLUMNS M where n.id=M.column3
ORDER BY 2

Open in new window

0
 

Author Comment

by:DaveThomasPilot
ID: 39199922
That gives me the data, but two many rows--each union will have the same number of records as MANYCOLUMNS----not what I want.
0
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Author Comment

by:DaveThomasPilot
ID: 39199934
I finally found something that I think works...

SELECT
C1.name,
C2.name,
C3.name,
.....

FROM MANY_COLUMNS

LEFT_OUTER_JOIN IDTONAME AS C1
ON MANYCOLUMNS.COLUMN1=C1.NAME
LEFT_OUTER_JOIN IDTONAME AS C2
ON MANYCOLUMNS.COLUMN2=C2.NAME
LEFT_OUTER_JOIN IDTONAME AS C3
ON MANYCOLUMNS.COLUMN3=C3.NAME


...

Maybe there's an easier way, but it seems to work.
0
 
LVL 25

Accepted Solution

by:
chaau earned 2000 total points
ID: 39199939
OK, I misunderstood you. In this case you need LEFT JOIN

select n1.name, n2.name, n3.name, etc. 
from MANYCOLUMNS M LEFT JOIN IDTONAME n1 ON n1.id=M.column1
LEFT JOIN IDTONAME n2 ON n2.id=M.column2
LEFT JOIN IDTONAME n3 ON n3.id=M.column3
etc.

Open in new window

0
 

Author Comment

by:DaveThomasPilot
ID: 39199959
Is that different than what I posted, or did you post pretty much the same time I did?
0
 
LVL 25

Expert Comment

by:chaau
ID: 39199963
I have not seen your answer when I was typing mine. Anyway, as you have found the answer yourself, you can request to close the question, or accept your answer as a solution
0
 
LVL 49

Expert Comment

by:PortletPaul
ID: 39199965
>>Maybe there's an easier way
nope: no easier way.
0

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