Delphi: Return database names from MySQL using Metadata

Question

I want to know if there is a way to return database names from MySQL using Delphi object TSQLConnection, I know that there is some methods that return table names or field names: TSQLConnection.getTableNames, TSQLConnection.GetFieldNames

but I can't find a way to get the databases on a specific server.

There s a method called OpenSchema in the TADOconnection object: TADOconnection.Openschema, that can return database names but in the TSQLConnection the method -protected not public- can't return database names.

P.S. I don't want to execute a query like 'show databases' or 'select * from information_schema.schemata'.

any body can help, thanks.

Answer 1

I tried this code and it worked, not sure if it will work for all MySQL, MariaDB versions and all Delphi versions but for me it workes, I am using delphi 6 and MySQL 4.0.25:

function GetMySQLDatabaseNames(AUserName, APassword, AHostName, APort: string; var 
AErrorMessage: String): TStrings;
var SQLConnection: TSQLConnection;
    ObjectCursor: ISQLCursor;
    Status: SQLResult;
    Counter: Integer;
    Precision: Smallint;
    Value: Pointer;
    IsBlank: LongBool;
begin
  Result:= TStringList.Create;
  SQLConnection:= TSQLConnection.Create(nil);

  with SQLConnection do
  begin
    ConnectionName:='dbnames';
    DriverName := 'mysql';
    Params.Clear;
    Params.Values['User_Name'] := AUserName;
    Params.Values['Password'] := APassword;
    Params.Values['HostName'] := AHostName;
    Params.Values['Database'] := 'mysql';
    Params.Values['Port'] := APort;
    LibraryName :='dbexpmda.dll';
    VendorLib := 'not used';
    GetDriverFunc :='getSQLDriverMySQLDirect';
    LoginPrompt :=False;
    try
      Connected := True;

      Status:= MetaData.getObjectList(eObjTypeDatabase, ObjectCursor);
      while Status = SQL_SUCCESS do
      begin
        Status:= ObjectCursor.getColumnPrecision(4, Precision);
        if Status = SQL_SUCCESS then
        begin
          Value:= AllocMem(Precision);
          Status:= ObjectCursor.getString(4, Value, IsBlank);
          if Status = SQL_SUCCESS then
            if not IsBlank then
              Result.Add(PChar(Value));
        end;
        Status:= ObjectCursor.Next;
      end;
      Connected := False;
      Free;
    except
      on E: Exception do
      begin
        AErrorMessage:= AErrorMessage + E.Message+ sLineBreak;
      end;
    end;
  end;
end;

Answer 2

With a query component you can get a list of databases with the following query:

SHOW DATABASES;

I have been looking for this answer for a longer time. Hopefully it will help others.