unit createdatabase;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, db, SynEdit, SynMemo, TntStdCtrls, WideStrings;

type
  TCreateDatabaseForm = class(TForm)
    editDBName: TTNTEdit;
    lblDBName: TLabel;
    comboCharset: TComboBox;
    lblCharset: TLabel;
    btnOK: TButton;
    btnCancel: TButton;
    lblCollation: TLabel;
    comboCollation: TComboBox;
    lblPreview: TLabel;
    SynMemoPreview: TSynMemo;
    procedure FormDestroy(Sender: TObject);
    procedure btnOKClick(Sender: TObject);
    procedure comboCharsetChange(Sender: TObject);
    procedure Modified(Sender: TObject);
    procedure editDBNameChange(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure FormCreate(Sender: TObject);
    procedure FormShow(Sender: TObject);
    function GetCreateStatement: WideString;
  private
    { Private declarations }
    dsCollations : TDataSet;
    defaultCharset : String;
    currentCollation : String;
  public
    { Public declarations }
    modifyDB : WideString;
  end;


implementation

uses main, helpers;

{$R *.dfm}


{**
  Fetch list with character sets and collations from the server
}
procedure TCreateDatabaseForm.FormCreate(Sender: TObject);
var
  charset: String;
begin
  InheritFont(Font);

  try
    dsCollations := Mainform.GetResults('SHOW COLLATION');
    // Detect servers default charset
    defaultCharset := Mainform.GetVar( 'SHOW VARIABLES LIKE '+esc('character_set_server'), 1 );
  except
    // Ignore it when the above statements don't work on pre 4.1 servers.
    // If the list(s) are nil, disable the combobox(es), so we create the db without charset.
  end;

  // Create a list with charsets from collations dataset
  comboCharset.Enabled := dsCollations <> nil;
  lblCharset.Enabled := comboCharset.Enabled;
  if comboCharset.Enabled then
  begin
    comboCharset.Items.BeginUpdate;
    dsCollations.First;
    while not dsCollations.Eof do
    begin
      charset := dsCollations.FieldByName('Charset').AsString;
      if comboCharset.Items.IndexOf(charset) = -1 then
        comboCharset.Items.Add(charset);
      dsCollations.Next;
    end;
    comboCharset.Items.EndUpdate;
  end;

  comboCollation.Enabled := dsCollations <> nil;
  lblCollation.Enabled := comboCollation.Enabled;

  // Setup SynMemoPreview
  SynMemoPreview.Highlighter := Mainform.SynSQLSyn1;
  SynMemoPreview.Font := Mainform.SynMemoQuery.Font;
end;


procedure TCreateDatabaseForm.FormDestroy(Sender: TObject);
begin
  if dsCollations <> nil then dsCollations.Close;
  FreeAndNil(dsCollations);
end;

{**
  Form gets displayed: Set default values.
}
procedure TCreateDatabaseForm.FormShow(Sender: TObject);
var
  selectCharset,
  currentCharset,
  sql_create : WideString;
  colpos: Integer;
begin
  if modifyDB = '' then
  begin
    Caption := 'Create database ...';
    editDBName.Text := '';
    editDBName.SetFocus;
    selectCharset := defaultCharset;
  end
  else begin
    Caption := 'Alter database ...';
    editDBName.Text := modifyDB;
    editDBName.SetFocus;
    editDBName.SelectAll;
    
    // Detect current charset and collation to be able to preselect them in the pulldowns
    sql_create := Mainform.GetVar('SHOW CREATE DATABASE '+Mainform.mask(modifyDB), 1);
    currentCharset := Copy( sql_create, pos('CHARACTER SET', sql_create)+14, Length(sql_create));
    currentCharset := GetFirstWord( currentCharset );
    if currentCharset <> '' then
      selectCharset := currentCharset
    else
      selectCharset := defaultCharset;
    currentCollation := '';
    colpos := pos('COLLATE', sql_create);
    if colpos > 0 then begin
      currentCollation := Copy( sql_create, colpos+8, Length(sql_create));
      currentCollation := GetFirstWord( currentCollation );
    end;
  end;

  // Preselect charset item in pulldown
  if comboCharset.Items.Count > 0 then
  begin
    if comboCharset.Items.IndexOf(selectCharset) > -1 then
      comboCharset.ItemIndex := comboCharset.Items.IndexOf(selectCharset)
    else
      comboCharset.ItemIndex := 0;
    // Invoke selecting default collation
    comboCharsetChange( Sender );
  end;

  // Invoke SQL preview
  Modified(Sender);
end;


{**
  Charset has been selected: Display fitting collations
  and select default one.
}
procedure TCreateDatabaseForm.comboCharsetChange(Sender: TObject);
var
  defaultCollation : String;
begin
  // Abort if collations were not fetched successfully
  if dsCollations = nil then
    Exit;

  // Fill pulldown with fitting collations
  comboCollation.Items.BeginUpdate;
  comboCollation.Items.Clear;
  dsCollations.First;
  while not dsCollations.Eof do
  begin
    if dsCollations.FieldByName('Charset').AsString = comboCharset.Text then
    begin
      comboCollation.Items.Add( dsCollations.FieldByName('Collation').AsString );
      if dsCollations.FieldByName('Default').AsString = 'Yes' then
        defaultCollation := dsCollations.FieldByName('Collation').AsString;
    end;
    dsCollations.Next;
  end;

  // Preselect default or current collation
  if currentCollation <> '' then
    defaultCollation := currentCollation;
  if comboCollation.Items.IndexOf(defaultCollation) > -1 then
    comboCollation.ItemIndex := comboCollation.Items.IndexOf(defaultCollation)
  else
    comboCollation.ItemIndex := 0;

  comboCollation.Items.EndUpdate;

  // Invoke SQL preview
  Modified(Sender);
end;


{**
  User writes something into editDBName
}
procedure TCreateDatabaseForm.editDBNameChange(Sender: TObject);
begin
  editDBName.Font.Color := clWindowText;
  editDBName.Color := clWindow;
  // Enable "OK"-Button by default
  btnOK.Enabled := True;
  try
    ensureValidIdentifier( editDBName.Text );
  except
    // Invalid database name
    if editDBName.Text <> '' then begin
      editDBName.Font.Color := clRed;
      editDBName.Color := clYellow;
    end;
    btnOK.Enabled := False;
  end;

  // Invoke SQL preview
  Modified(Sender);
end;


{**
  Create the database
}
procedure TCreateDatabaseForm.btnOKClick(Sender: TObject);
var
  sql : WideString;
  AllDatabases, Unions, ObjectsLeft: TWideStringList;
  ObjectsInNewDb, ObjectsInOldDb: TDataset;
  OldObjType, NewObjType: TListNodeType;
begin
  if modifyDB = '' then try
    sql := GetCreateStatement;
    Mainform.ExecUpdateQuery( sql );
    // Close form
    ModalResult := mrOK;
  except
    On E:Exception do
      MessageDlg( 'Creating database "'+editDBName.Text+'" failed:'+CRLF+CRLF+E.Message, mtError, [mbOK], 0 );
    // Keep form open
  end else try
    sql := 'ALTER DATABASE ' + Mainform.mask( modifyDB );
    if comboCharset.Enabled and (comboCharset.Text <> '') then
    begin
      sql := sql + ' CHARACTER SET ' + comboCharset.Text;
      if comboCollation.Enabled and (comboCollation.Text <> '') then
        sql := sql + ' COLLATE ' + comboCollation.Text;
    end;
    if modifyDB = editDBName.Text then begin
      // Alter database
      Mainform.ExecUpdateQuery(sql);
    end else begin
      // Rename database
      ObjectsInOldDb := MainForm.RefreshDbTableList(modifyDB);
      AllDatabases := Mainform.GetCol('SHOW DATABASES');
      if AllDatabases.IndexOf(editDBName.Text) = -1 then begin
        // Target db does not exist - create it
        Mainform.ExecUpdateQuery(GetCreateStatement);
      end else begin
        // Target db exists - warn if there are tables with same names
        ObjectsInNewDb := MainForm.RefreshDbTableList(editDBName.Text);
        while not ObjectsInNewDb.Eof do begin
          NewObjType := GetDBObjectType(ObjectsInNewDb.Fields);
          ObjectsInOldDb.First;
          while not ObjectsInOldDb.Eof do begin
            OldObjType := GetDBObjectType(ObjectsInOldDb.Fields);
            if not (OldObjType in [lntTable, lntCrashedTable, lntView]) then
              Raise Exception.Create('Database "'+modifyDB+'" contains stored routine(s), which cannot be moved.');
            if (ObjectsInOldDb.FieldByName(DBO_NAME).AsWideString = ObjectsInNewDb.FieldByName(DBO_NAME).AsWideString)
              and (OldObjType = NewObjType) then begin
              // One or more objects have a naming conflict
              Raise Exception.Create('Database "'+editDBName.Text+'" exists and has objects with same names as in "'+modifyDB+'"');
            end;
            ObjectsInOldDb.Next;
          end;
          ObjectsInNewDb.Next;
        end;
        if MessageDlg('Database "'+editDBName.Text+'" exists. But it does not contain objects with same names as in '+
          '"'+modifyDB+'", so it''s uncritical to move everything.'+CRLF+CRLF+'Move all objects to "'+editDBName.Text+'"?',
          mtConfirmation, [mbYes, mbCancel], 0) <> mrYes then
          Exit;
      end;
      // Move all tables, views and procedures to target db
      ObjectsInOldDb.First;
      sql := 'RENAME TABLE ';
      while not ObjectsInOldDb.Eof do begin
        sql := sql + Mainform.mask(modifyDb)+'.'+Mainform.mask(ObjectsInOldDb.FieldByName(DBO_NAME).AsWideString)+' TO '+
          Mainform.mask(editDBName.Text)+'.'+Mainform.mask(ObjectsInOldDb.FieldByName(DBO_NAME).AsWideString)+', ';
        ObjectsInOldDb.Next;
      end;
      Delete(sql, Length(sql)-1, 2);
      Mainform.ExecUpdateQuery(sql);
      Mainform.ClearDbTableList(modifyDB);
      Mainform.ClearDbTableList(editDBName.Text);
      // Last step for renaming: drop source database
      ObjectsLeft := TWideStringList.Create;
      if Assigned(Mainform.InformationSchemaTables) then begin
        // Last check if old db is really empty, before we drop it. Especially triggers need to be checked.
        Unions := TWideStringList.Create;
        if Mainform.InformationSchemaTables.IndexOf('TABLES') > -1 then
          Unions.Add('SELECT 1 FROM '+Mainform.mask(DBNAME_INFORMATION_SCHEMA)+'.TABLES WHERE TABLE_SCHEMA='+esc(modifyDB));
        if Mainform.InformationSchemaTables.IndexOf('ROUTINES') > -1 then
          Unions.Add('SELECT 1 FROM '+Mainform.mask(DBNAME_INFORMATION_SCHEMA)+'.ROUTINES WHERE ROUTINE_SCHEMA='+esc(modifyDB));
        if Mainform.InformationSchemaTables.IndexOf('TRIGGERS') > -1 then
          Unions.Add('SELECT 1 FROM '+Mainform.mask(DBNAME_INFORMATION_SCHEMA)+'.TRIGGERS WHERE TRIGGER_SCHEMA='+esc(modifyDB));
        if Unions.Count = 1 then
          ObjectsLeft := Mainform.GetCol(Unions[0])
        else if Unions.Count > 1 then
          ObjectsLeft := Mainform.GetCol('(' + implodestr(') UNION (', Unions) + ')');
      end;
      if ObjectsLeft.Count = 0 then begin
        Mainform.ExecUpdateQuery('DROP DATABASE '+modifyDB);
      end;
      FreeAndNil(ObjectsLeft);
    end;
    // Close form
    ModalResult := mrOK;
  except
    On E:Exception do
      MessageDlg( 'Altering database "'+editDBName.Text+'" failed:'+CRLF+CRLF+E.Message, mtError, [mbOK], 0 );
    // Keep form open
  end;
end;


{**
  Called on each change
}
procedure TCreateDatabaseForm.Modified(Sender: TObject);
begin
  SynMemoPreview.Clear;
  SynMemoPreview.Text := GetCreateStatement;
end;


{**
  Generate CREATE DATABASE statement, used for preview and execution
}
function TCreateDatabaseForm.GetCreateStatement: WideString;
begin
  Result := 'CREATE DATABASE ' + Mainform.mask( editDBName.Text );
  if comboCharset.Enabled and (comboCharset.Text <> '') then
  begin
    Result := Result + ' /*!40100 CHARACTER SET ' + comboCharset.Text;
    if comboCollation.Enabled and (comboCollation.Text <> '') then
      Result := Result + ' COLLATE ' + comboCollation.Text;
    Result := Result + ' */';
  end;
end;


{**
  Form gets closed: Reset potential modifyDB-value.
}
procedure TCreateDatabaseForm.FormClose(Sender: TObject; var Action:
    TCloseAction);
begin
  modifyDB := '';
end;


end.