Solved

ADo select double numbers

Posted on 2009-04-03
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Last Modified: 2013-11-23
I have a table with
Name, Number, Extention, Group
Eacht name has 2 extentions but the number is the same.

Now I need to selct one name from each Number. I am still getting double records as result.
I have
Jack, 3, 124, Marketing and I have Jack 1, 3, 123, Marketing
I need to select only one of these
My code is 
     SQL.Add('Select  distinct M_number, M_name, M_Extention, Group');
     SQL.Add('From Employees);
     SQL.Add('Where (Group = '+QuotedStr(Group)+')');
 
 
What is wrong in this?

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Question by:Nayel
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9 Comments
 
LVL 37

Expert Comment

by:Geert Gruwez
ID: 24057849
you are selecting multiple different ones with distinct not 1

and use parameters for performance, allways better !
and Group is a reserved word (bettter to use other column name)





as i dunno what database ... for oracle:
SELECT M_number, M_name, M_Extention, Group
FROM (SELECT M_number, M_name, M_Extention, Group, RANK() OVER (PARTITION BY M_Number ORDER BY M_Number) X
            WHERE GROUP = :AGRoup)
WHERE X = 1

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Author Comment

by:Nayel
ID: 24057862
I am using Access
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LVL 37

Expert Comment

by:Geert Gruwez
ID: 24057904
that's not a database ... it's a flat file :)

SELECT E.*
FROM Employees E,
  (SELECT M_Number, Min(M_Name) XName FROM Employees Group By M_Number) X
WHERE E.M_Number = X.M_Number
  AND E.M_Name = X.XName

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Author Comment

by:Nayel
ID: 24057920
No no.. I am using Delphi which is connected to Access. And the query should be written in an ADOQUERY
0
 
LVL 37

Expert Comment

by:Geert Gruwez
ID: 24057950
just kidding
var AdoQuery: TAdoQuery;
begin
  AdoQuery.SQL.Text := 
    'SELECT E.* FROM Employees E,           '+
    '  (SELECT M_Number, Min(M_Name) XName  '+ 
    '   FROM Employees Group By M_Number) X '+
    'WHERE E.M_Number = X.M_Number          '+
    '  AND E.M_Name = X.XName               '+
    '  AND E.Group = :GROUP                 ';
  AdoQuery.Parameters.ParamByName('GROUP').Value := Group;
  AdoQuery.Open;

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Author Comment

by:Nayel
ID: 24058035
Getting a fault.
0
 
LVL 37

Expert Comment

by:Geert Gruwez
ID: 24058039
and that would be ?

i tried to smell what it was, but i have a small cold ...
0
 

Author Comment

by:Nayel
ID: 24058073
A syntaxerror in expression Min(M_Name) XName
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LVL 37

Accepted Solution

by:
Geert Gruwez earned 50 total points
ID: 24058080
I'm not supergood in access,
I try to stay away from it,
but try this:
var AdoQuery: TAdoQuery;
begin
  AdoQuery.SQL.Text := 
    'SELECT E.* FROM Employees E,              '+
    '  (SELECT M_Number, Min(M_Name) AS XName  '+ 
    '   FROM Employees Group By M_Number) AS X '+
    'WHERE E.M_Number = X.M_Number             '+
    '  AND E.M_Name = X.XName                  '+
    '  AND E.Group = :GROUP                    ';
  AdoQuery.Parameters.ParamByName('GROUP').Value := Group;
  AdoQuery.Open;

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