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Query from a query

Posted on 1998-06-02
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Last Modified: 2010-04-06
Is it possible to use the result from a query in another TQuery object.  For instance, Have a query that returns a data set.  Then have another query that returns the sum of one of the columns in the first dataset?  

I'm trying to avoid having the same query in multiple places!

Roger Webb
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Question by:Whytboy
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8 Comments
 
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Expert Comment

by:ZifNab
ID: 1349707
Sure, why not?
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Author Comment

by:Whytboy
ID: 1349708
And that would be accomplished .... how??


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Expert Comment

by:ZifNab
ID: 1349709
Ooops, sorry misread your question, don't know if that's possible.
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Accepted Solution

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yunic earned 150 total points
ID: 1349710
 Query1.SQL.Text:='select attr_op, attr_dolzina from meta_sif_attr';
  Query1.Open;
  Query2.SQL.Text:='select sum('+query1.fields[1].fieldname+') from meta_sif_attr';
  query2.Open;
  writeln(Query2.fields[0].AsString);


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Author Comment

by:Whytboy
ID: 1349711
Problem with that is that if you include a where clause so make query1 a subset of data.. you would have to include the where clause in query2 as well...
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Expert Comment

by:yunic
ID: 1349712
that's true.

one solution would be to copy all text from query1 to query2 replacing just fields between 'select ' and ' from'.

actually it was meant to be used that way especially if query is joining more tables.



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Expert Comment

by:yunic
ID: 1349713
so it would look like this

query2.sql.text:='select sum('+query1.fields[1].fieldname+') '+
  copy(query1.sql.text, pos('from',query1.sql.text),
    length(query1.sql.text)-pos('from',query1.sql.text));

check syntax, i wrote it know, didn't checked
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Author Comment

by:Whytboy
ID: 1349714
Adjusted points to 150
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