Add feature #1843670 "Multi-table Automated File Exporting"

The output filename gets parsed and the eventually existing "<table>" pattern gets replaced by either "header", "table1", "table2", ..., or "footer". That means, the single SQL files won't be complete in the end, as the header and footer is missing in the table-files. Not 100% sure if this is a good strategy. For me it seemed like the best/fast/lame way of working around the fact that the header potentially contains a CREATE DATABASE statement.

source/exportsql.dfm

@@ -177,6 +177,8 @@ object ExportSQLForm: TExportSQLForm
           Width = 304
           Height = 21
           Anchors = [akLeft, akTop, akRight]
+          ParentShowHint = False
+          ShowHint = True
           TabOrder = 1
           OnDblClick = btnFileBrowseClick
         end

source/exportsql.pas

@@ -94,6 +94,7 @@ type
     procedure SaveSettings;
   private
     { Private declarations }
+    function InitFileStream(TableName: String; OldStream: TFileStream = nil): TFileStream;
   public
     { Public declarations }
   end;
@@ -135,6 +136,9 @@ const
   // Default output compatibility
   SQL_VERSION_DEFAULT = SQL_VERSION_ANSI;
 
+  // Pattern for use in creating destination files
+  TABLENAME_PATTERN = '<table>';
+
 var
   appHandles: array of THandle;
   cancelDialog: TForm = nil;
@@ -279,6 +283,9 @@ begin
   if EditFileName.Text = '' then
     EditFileName.Text := ExtractFilePath(paramstr(0)) + 'export.sql';
 
+  // Tell the user how to use the table pattern  
+  EditFileName.Hint := 'Usage for generating one file per table: c:\foo\bar_'+TABLENAME_PATTERN+'.sql';
+
   validateControls(Sender);
   generateExampleSQL;
 end;
@@ -426,6 +433,50 @@ begin
 end;
 
 
+{**
+  Parse destination filename for variables like %table% and create the file
+  If an existing filestream is passed, check if it should be reused, depending on the "Part"
+  @return TFileStream|Nil
+}
+function TExportSQLForm.InitFileStream(TableName: String; OldStream: TFileStream = nil): TFileStream;
+var
+  ParsedFileName, FileName, FilePath : String;
+begin
+  Result := nil;
+
+  // Parse filename
+  FilePath := ExtractFilePath(EditFileName.Text);
+  FileName := ExtractFileName(EditFileName.Text);
+  FileName := StringReplace(FileName, TABLENAME_PATTERN, TableName, [rfIgnoreCase]);
+  ParsedFileName := FilePath + GoodFileName(FileName);
+
+  // Reuse the old stream if its filename has not changed
+  if (OldStream <> nil) and (OldStream.FileName = ParsedFileName) then
+  begin
+    Result := OldStream;
+    Exit;
+  end;
+
+  // Filename has changed, so close the old file.
+  if OldStream <> nil then
+    OldStream.Free;
+
+  // Warn about overwriting target file
+  if FileExists(ParsedFileName) then begin
+    if MessageDlg('Overwrite file "'+ParsedFileName+'" ?', mtConfirmation, [mbYes, mbCancel], 0 ) <> mrYes  then
+      Exit;
+  end;
+
+  // Create the file
+  try
+    Result := TFileStream.Create(ParsedFileName, fmCreate);
+  except
+    MessageDlg('File "'+ParsedFileName+'" could not be opened!' +  CRLF + 'Maybe in use by another application?', mterror, [mbOK], 0);
+    Result.Free;
+  end;
+end;
+
+
 procedure TExportSQLForm.btnExportClick(Sender: TObject);
 var
   f                         : TFileStream;
@@ -487,12 +538,6 @@ begin
   todb := radioOtherDatabase.Checked;
   tohost := radioOtherHost.Checked;
 
-  // Warn about overwriting target file
-  if tofile and FileExists(EditFileName.Text) then begin
-    if MessageDlg('Overwrite file "'+EditFileName.Text+'" ?', mtConfirmation, [mbYes, mbCancel], 0 ) <> mrYes  then
-      Exit;
-  end;
-
   // export!
   pageControl1.ActivePageIndex := 0;
   Screen.Cursor := crHourGlass;
@@ -523,13 +568,11 @@ begin
     // Extract name part of selected target version
     target_version := StrToIntDef( target_versions.Names[ comboTargetCompat.ItemIndex ], SQL_VERSION_DEFAULT );
     max_allowed_packet := MakeInt( cwin.GetVar( 'SHOW VARIABLES LIKE ' + esc('max_allowed_packet'), 1 ) );
-    try
-      f := TFileStream.Create(EditFileName.Text, fmCreate);
-    except
-      messagedlg('File "'+EditFileName.Text+'" could not be opened!' +  crlf + 'Maybe in use by another application?', mterror, [mbOK], 0);
-      f.free;
+    f := InitFileStream('header');
+    if f = nil then
+    begin
       Screen.Cursor := crDefault;
-      abort;
+      Abort;
     end;
     wfs(f, '# ' + APPNAME + ' Dump ');
     wfs(f, '#');
@@ -725,6 +768,16 @@ begin
 
       if exporttables then
       begin
+        if tofile then
+        begin
+          f := InitFileStream(checkListTables.Items[i], f);
+          if f = nil then
+          begin
+            Screen.Cursor := crDefault;
+            Abort;
+          end;
+        end;
+
         dropquery := '';
         if comboTables.ItemIndex = TAB_DROP_CREATE then begin
           if tofile then
@@ -1131,6 +1184,16 @@ begin
       end;
     end;
 
+    if tofile then
+    begin
+      f := InitFileStream('footer', f);
+      if f = nil then
+      begin
+        Screen.Cursor := crDefault;
+        Abort;
+      end;
+    end;
+
     // Restore old value for SQL_MODE
     if (tofile or tohost) and (target_version = SQL_VERSION_ANSI) then
     begin