How to "preserve" the ClientDataSet returned by TSQLConnection.Execute ??

Posted on 2003-03-10
Medium Priority
Last Modified: 2008-02-20
What I want to do:
- spname is the name of any stored procedure that returns rows.
- GetData should initialize mycds with the result of this stored procedure

What I get:
- an empty dataset (mycds) and an access violation when I try to access its

procedure TMyClass.GetData(spname: String; var mycds: TCustomClientDataSet);

    // objSQL is a var declared outside the procedure.
    // SqlConn is a TSQLConnection instance. The connection is established during "Create"

    objSQL := TSQL.Create;
    objSQL.SqlConn.Execute('SELECT * FROM ' + spname', nil, @mycds);

procedure TMyClass.CallGetData;
    cds: TCustomClientDataSet;
    GetData('some_Select_sp', cds);
    while not cds.eof do begin
      // something;

Question by:hellspawn_9999
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Expert Comment

ID: 8102846
objSQL.SqlConn.Execute('SELECT * FROM ' + spname', nil, @mycds);

I'm not sure that you can get stored procedure results form SQLConnection's Execute. You must instead use TSQLStoredProc component.
anyway to get results of stored procedure you shouldn't use SELECT * FROM.. but EXEC or simply call your stored procedure

wbr, mo.

Author Comment

ID: 8105195

I'm using Interbase at the server side.

If I use EXEC I will be able to retrieve only the first row of the resultset.

I sucessully used the Execute to get my resultset with Kylix 2. The only difference is in that version the "mycds" variable is a local variable (not a parameter), and the return parameter is a String variable that returns the XMLData to the calling procedure/application (see sample below).

I tried to transfer that code to client side in order to improve performance by skipping the Data=>XML conversion, then I got caught in that situation.

(* this code is ok *)

procedure TMyClass.GetData(spname, XMLResult: String);
mycds: TCustomClientDataSet;

   objSQL := TSQL.Create;
   objSQL.SqlConn.Execute('SELECT * FROM ' + spname', nil, @mycds);
   XMLResult := mycds.XMLData;


Expert Comment

ID: 9316859
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Accepted Solution

hellspawn_9999 earned 0 total points
ID: 9333408
Problem was the parameter type (TCustomClientDataSet) was not compatible with the variable returned by Execute (TSQLDataSet).

Please refund.

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