capture values from a simple select query TADOQuery Delphi - mysql

Question

I am having issues returning the value gotten from a simple SELECT query using TADOQuery
here is my code below:
dbWizconQuery.SQL.Clear;
dbWizconQuery.SQL.Add('SELECT * FROM test');
tb_wizconValues.Items.Add('' + dbWizconQuery.SQL.GetText);
dbWizconQuery.ExecSQL;
processed := IntToStr(dbWizconQuery.FieldByName ('input' ).Value);
tb_wizconValues.Items.Add('' + processed);
I get the first print out in my textbox ok, with the SQL String
but then i dont get the value coming out.
Can you see why this might be?
Processed is a String and input is an INT(5) which comes out AsString
Kind Regards,
Jordan

Answer 1

in delphi ExecSQL is used when you want to do an
UPDATE,INSERT,DELETE
when you want to do a select call open or just set the query to
active := true;
you can get multiple results back by using this code:
dbWizconQuery.SQL.Clear;
dbWizconQuery.SQL.Text := 'SELECT * FROM test';
dbWizconQuery.Open; // or dbWizconQuery.Active := True;
while not dbWizconQuery.eof do
begin
ShowMessage(dbWizconQuery.FieldByName('FieldName').AsString); // this shows the fields value
dbWizconQuery.Next; //use this line or you will get an infinite loop
end;
dbWizconQuery.Close; //closes the dataset
for executing statements like UPDATE,INSERT,DELETE use it like this:
dbWizconQuery.SQL.Text := 'DELETE FROM test WHERE ID = 1';
dbWizconQuery.ExecSQL;

Answer 2

ExecSQL is used for statements that don't return a rowset, such as INSERT, DELETE and UPDATE. For a SELECT, you need to use Open instead:
dbWizconQuery.SQL.Clear;
dbWizconQuery.SQL.Add('SELECT * FROM test');
tb_wizconValues.Items.Add('' + dbWizconQuery.SQL.GetText);
dbWizconQuery.Open;
processed := IntToStr(dbWizconQuery.FieldByName ('input' ).Value);
tb_wizconValues.Items.Add('' + processed);
For more info, see the documentation for TDataSet