Database and zeos manual
lazarus / 16-Databases

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notebook · 2011-08-03 20:01

I try manual zeoslib and work fine, if I all put in event on click.

I have second example but don' t work.


Code: [Select]unit Unit2;

interface

uses
  Classes, SysUtils,sqldb,db,Types,Dialogs,ZConnection,
  ZDataset, ZSqlProcessor, ZStoredProcedure,DBGrids;
type
  connectiom=class(TObject)
    public
   function q(query: string): TDataSet;
   private
     c : TZConnection;
     qu : TZQuery;
     ds : TDataSource;

  end;



implementation


 function connectiom.q(query: string): TDataSet;
begin
  c := TZConnection.Create(nil);
  qu:=TZQuery.Create(nil);
  ds:=TDataSource.Create(nil);

  c.Catalog:='postgres';
  c.Database:='postgres';
  c.HostName:='127.0.0.1';
  c.Password:='postgres';
  c.port:=5432;
  c.Protocol:='postgresql-8';
  c.User:='postgres';

 qu.Connection:=c;
 qu.SQL.Text:=query;
 ds.DataSet:=qu;

 c.Connect;
 q.Active:=true;

end;

 end.





Code: [Select]unit Unit1;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs,
StdCtrls,
  DBGrids, ZConnection, ZDataset, unit2, db;

type

  { TForm1 }

  TForm1 = class(TForm)
    Button1: TButton;
    DBGrid1: TDBGrid;
    procedure Button1Click(Sender: TObject);
  private
   p : connectiom;
   ds : TDataSource;

  public
    { public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.lfm}

{ TForm1 }

procedure TForm1.Button1Click(Sender: TObject);
begin
   p:=connectiom.Create;
   ds:=TDataSource.Create(nil);


 ds.DataSet:=  p.q('select * from my_table');

   DBGrid1.DataSource:= ds;


end;

end.


what is wrong in unit1?
Is unit2 correct?

Can function  return dataset?

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nicke85 · 2011-08-03 21:47

What is with this topic?
http://www.lazarus.freepascal.org/index.php/topic,14051.0.html
Is that the same topic twice?

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notebook · 2011-08-04 05:16

Quote from: nicke85 on August 03, 2011, 11:47:37 pmWhat is with this
topic?
http://www.lazarus.freepascal.org/index.php/topic,14051.0.html

This work If I put code on event.
I want create seperate class for connection and query, and yet one
class for  BL.

Quote from: nicke85 on August 03, 2011, 11:47:37 pmIs that the same
topic twice?

similar but diferent.

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nicke85 · 2011-08-04 08:32

Quote from: notebook on August 04, 2011, 07:16:52 amI want create
seperate class for connection and query, and yet one class for  BL.

You don't need to do that.Why do you need connection Class?
In zeos you have two elements for that ZConnectionGroup and
ZGroupedConnection.These two elements is used to define one parameter
for multiple connection so
just create these and then when need create ZConnection in runtime.

In your unit1 you call function connectiom.q and create dataset but
where you destroy or free that dataset later?

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notebook · 2011-08-05 11:21

Quote from: nicke85 on August 04, 2011, 10:32:06 amQuote from:
notebook on August 04, 2011, 07:16:52 amI want create seperate class
for connection and query, and yet one class for  BL.

You don't need to do that.Why do you need connection Class?
In zeos you have two elements for that ZConnectionGroup and
ZGroupedConnection.These two elements is used to define one parameter
for multiple connection so
just create these and then when need create ZConnection in runtime.

In your unit1 you call function connectiom.q and create dataset but
where you destroy or free that dataset later?

Thank you.

Can I return  data as  dataset and how?

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notebook · 2011-08-05 19:23

solved

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Menkaura · 2014-04-03 19:53

Quote from: notebook on August 03, 2011, 10:01:56 pmI try manual
zeoslib and work fine, if I all put in event on click.

I have second example but don' t work.


Code: [Select]unit Unit2;

interface

uses
  Classes, SysUtils,sqldb,db,Types,Dialogs,ZConnection,
  ZDataset, ZSqlProcessor, ZStoredProcedure,DBGrids;
type
  connectiom=class(TObject)
    public
   function q(query: string): TDataSet;
   private
     c : TZConnection;
     qu : TZQuery;
     ds : TDataSource;

  end;



implementation


 function connectiom.q(query: string): TDataSet;
begin
  c := TZConnection.Create(nil);
  qu:=TZQuery.Create(nil);
  ds:=TDataSource.Create(nil);

  c.Catalog:='postgres';
  c.Database:='postgres';
  c.HostName:='127.0.0.1';
  c.Password:='postgres';
  c.port:=5432;
  c.Protocol:='postgresql-8';
  c.User:='postgres';

 qu.Connection:=c;
 qu.SQL.Text:=query;
 ds.DataSet:=qu;

 c.Connect;
 q.Active:=true;

end;

 end.





Code: [Select]unit Unit1;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs,
StdCtrls,
  DBGrids, ZConnection, ZDataset, unit2, db;

type

  { TForm1 }

  TForm1 = class(TForm)
    Button1: TButton;
    DBGrid1: TDBGrid;
    procedure Button1Click(Sender: TObject);
  private
   p : connectiom;
   ds : TDataSource;

  public
    { public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.lfm}

{ TForm1 }

procedure TForm1.Button1Click(Sender: TObject);
begin
   p:=connectiom.Create;
   ds:=TDataSource.Create(nil);


 ds.DataSet:=  p.q('select * from my_table');

   DBGrid1.DataSource:= ds;


end;

end.


what is wrong in unit1?
Is unit2 correct?

Can function  return dataset?


in unit2

change   q.Active:=true;  to qu.Active:=true;

and add following line

q:=ds.DataSet;

That works for me.