Lazarus, PostgreSQL, "Field not found" error

[Ali KOCA]

Code: MySQL  [Select][+][-]

1. select  kullanici_ismi as is_im
2. FROM kullanicilar;
3.  

And there is both "i" and "_".

I don't think it's about the Turkish locale. And I've never had such a problem except postgres.

[altanbozoglu]

Hi;
It's been a long time ago, but maybe this solution might work.
The problem is that lazarus and fpc treat unicode strings differently.
If you test with a simple console application, you will see that the queries are running. The problem is somewhat related to the cwstring unit.
In my opinion, the best thing to do is to run the database part as a dynamic link library. I made a very simple example below.

Library

Code: Pascal  [Select][+][-]

1.  
2. library mydatalink;
3.  
4. {$mode objfpc}{$H+}
5.  
6. uses
7.    Classes, SysUtils, parentunit, ZDataset, ZConnection, db;
8.  
9. function ServerCnn():Boolean cdecl;
10. Begin
11.   lasterror := False;
12.  try
13.   SQLServerCnn := TZConnection.Create(nil);
14.   SQLServerCnn.Protocol  := 'postgresql';
15.   SQLServerCnn.Database  := 'yourdatabasename';
16.   SQLServerCnn.User      := 'usernamame';
17.   SQLServerCnn.Password  := 'password';
18.   SQLServerCnn.HostName  := 'serverip';
19.   SQLServerCnn.Connected := True;
20.   Result := SQLServerCnn.Connected;
21.   Except on E : Exception do
22.   Begin
23.     lasterror    := True;
24.     ErrorClass   := E.ClassName;
25.     ErrorMessage := E.Message;
26.   end;
27.  end;
28. end;
29.  
30. function SQLrun( SQLText: String):TDataSet; cdecl;
31. var
32.  sql:TZQuery;
33. Begin
34.   lasterror := False;
35.   try
36.     sql := TZQuery.Create(SQLServerCnn);
37.     sql.Connection := SQLServerCnn;
38.     sql.SQL.Text := SQLText;
39.     sql.Open;
40.     Result := sql;
41.     Except on E : Exception do
42.     Begin
43.       lasterror    := True;
44.       ErrorClass   := E.ClassName;
45.       ErrorMessage := E.Message;
46.       Result := nil;
47.     end;
48.   end;
49. end;
50.  
51. function ErrorExsist():Boolean; cdecl;
52. Begin
53.   Result := lasterror;
54. end;
55.  
56. function GetErrorClass():String; cdecl;
57. Begin
58.   Result := ErrorClass;
59. end;
60.  
61. function GetErrorMessage():String; cdecl;
62. Begin
63.   Result := ErrorMessage;
64. end;
65.  
66.  
67. exports
68. ServerCnn, SQLrun, ErrorExsist, GetErrorClass, GetErrorMessage;
69. end.
70.  
71. //--------------------------------------------------------------
72.  
73. unit parentunit;
74.  
75. {$mode objfpc}{$H+}
76.  
77. interface
78.  
79. uses
80.   Classes, ZConnection;
81.  
82.  type
83.  
84.    { TParentObject }
85.  
86.    TParentObject = class(TComponent)
87.    private
88.    public
89.      connected:Boolean;
90.      constructor Create(AOwner: TComponent); override;
91.    end;
92.  
93.  var
94.    ParentObj:TParentObject;
95.    lasterror:Boolean;
96.    ErrorClass:String;
97.    ErrorMessage:String;
98.    SQLServerCnn:TZConnection;
99.  
100. implementation
101.  
102.  
103.  
104. { TParentObject }
105.  
106. constructor TParentObject.Create(AOwner: TComponent);
107. begin
108.    inherited;
109. end;
110.  
111.  
112. end.
113.  

Note: After compiling the dynamic link library, remember to copy it to /usr/lib

Sample Application

Code: Pascal  [Select][+][-]

1.  
2.   //...
3.   function ServerCnn():Boolean cdecl; external 'libmydatalink.so';
4.   function SQLrun( SQLText: String):TDataSet; cdecl; external 'libmydatalink.so';
5.   function ErrorExsist():Boolean; cdecl; external 'libmydatalink.so';
6.   function GetErrorClass():String; cdecl; external 'libmydatalink.so';
7.   function GetErrorMessage():String; cdecl; external 'libmydatalink.so';
8.  
9. var
10.   Form1: TForm1;
11.  
12. implementation
13.  
14. {$R *.lfm}
15.  
16. { TForm1 }  
17.  
18. procedure TForm1.Button1Click(Sender: TObject);
19. begin
20.  if ServerCnn() then
21.    ShowMessage('Connected');
22. end;
23.  
24. procedure TForm1.Button2Click(Sender: TObject);
25. begin
26.   DataSource1.DataSet := SQLrun('select * from testtable');
27.   if ErrorExsist() then
28.   Memo1.Lines.Text := GetErrorMessage();
29. end;
30.        
31.  

Cheers..