[fpc-pascal]MySQL under Windows

[Fernando Lozano]

Hi there,

I am using FPC 1.0.6 under Windows 98 and MySQL 3.23.49.

The simple test program bellow generates a run-time error 103 on the first write/writeln call unless I define the variable filler. Looks like binary incompatibilities between the pre-compiled Units and the MySQL DLL. Maybe you should distribute the libmysql.dll used when compiling FPC alongside the binaries. :-)

But when I tried to build a test program using FCL, I get an Internal Error when I try to open the Dataset. This other test program is also included so you can check what I've done wrong or help me find a workaround like the filler variable on the first test.

Please let me also ask what's the proper way to check for error (can't connect, wrong password, SQL syntax, no rights, ...) when using the FCL database classes.

[]s, Fernando Lozano


// first test program

program testemysql;

uses mysql;

const
    host = 'linuxfs';
    banco = 'poo';
    login = 'teste';
    senha = 'senha';
    
var
    bd : PMYSQL;
    qmysql : TMYSQL;
    filler : string;
    sql : ansistring;
    res : PMYSQL_RES;
    row : TMYSQL_ROW;

procedure erro (bd : PMYSQL; msg : string);
begin
    writeln (stderr, msg);
    writeln (stderr, mysql_error(bd));
    readln;
    halt(1); 
end;

begin
    filler := '';
    bd :=  mysql_connect (PMysql (@qmysql), host, login, senha);
    if bd = Nil then
	erro (PMysql (@qmysql), 'Can't conect to MySQL server');

    if mysql_select_db (bd, banco) < 0 then
	erro (bd, 'Can't select the database ' + banco);
    
    sql := 'SELECT name, e_mail FROM addressbook';
    if mysql_query (bd, PChar (sql)) < 0 then
	erro (bd, 'Error on SELECT');
    
    res := mysql_store_result (bd); 
    if (res = nil) then
	writeln ('There are no records')
    else begin
	row := mysql_fetch_row (res);
	while (row <> nil) do begin
	    write ('name: ', row[0], ', ');
	    write ('e-mail: ', row[1]);
	    writeln;
	    row := mysql_fetch_row (res);
	end;
	mysql_free_result (res);
    end;
	
    mysql_close (bd);
    readln;
end.

// second test

program testedbmysql;

uses db, mysqldb;

const
    host = 'linuxfs';
    banco = 'poo';
    login = 'teste';
    senha = 'senha';
    
var
    bd : TMysqlDataset;
    filler : string;

procedure erro (bd : TMysqlDataset; msg : string);
begin
    //writeln (stderr, msg);
    //writeln (stderr, mysql_error(bd));
    writeln (msg);
    //writeln (mysql_error(bd));
    readln;
    halt(1); 
end;

begin
    //filler := '';
    bd := TMysqlDataset.Create (nil);
    bd.Host := host;
    bd.Database := banco;
    bd.User := login;
    bd.Password := senha;
    
    bd.SQL.text := 'SELECT numero, saldo FROM conta_corrente';
    bd.Open;
    
    while not bd.EOF do begin
	write ('numero: ', bd.Fields[0].AsString, ', ');
	write ('saldo: ', bd.Fields[1].AsString);
	writeln;
	bd.Next;
    end;

    bd.Close;
    bd.Free;
    readln;
end.