ClientDataSet的隐含功能-3

begin
　　try
　　Result := CreateOleObject(\’ADODB.Connection\’);
　　Result.CursorLocation := adUseServer;
　　Result.IsolationLevel := adXactCursorStability;
　　Result.Mode := adModeReadWrite;
　　Result.Provider := \’SQLOLEDB.1\’;
　　except
　　if not VarIsEmpty(Result) then Result := Unassigned;
　　end;
　　end;
　　procedure FreeConnection(var cnn: OleVariant);
　　begin
　　if not VarIsEmpty(cnn) then
　　begin
　　if cnn.State <> adStateClosed then cnn.Close;
　　cnn := Unassigned;
　　end;
　　end;
　　function CreateRecordset: OleVariant;
　　begin
　　try
　　Result := CreateOleObject(\’ADODB.Recordset\’);
　　Result.CacheSize := 1000;
　　Result.CursorType := adOpenStatic;
　　Result.CursorLocation := adUseServer;
　　Result.LockType := adLockOptimistic;
　　except
　　if not VarIsEmpty(Result) then Result := Unassigned;
　　end;
　　end;
　　procedure FreeRecordset(var rst: OleVariant);
　　begin
　　FreeConnection(rst);
　　end;
　　function CreateCommand: OleVariant;
　　begin
　　try
　　Result := CreateOleObject(\’ADODB.Command\’);
　　Result.CommandType := adCmdText;
　　Result.CommandTimeout := 5;
　　except
　　if not VarIsEmpty(Result) then Result := Unassigned;
　　end;
　　end;
　　procedure FreeCommand(var cmd: OleVariant);
　　begin
　　if not VarIsEmpty(cmd) then cmd := Unassigned;
　　end;
　　function ConnectToDB(cnn: OleVariant; const db, host, usr, pwd: string): Boolean;
　　begin
　　Result := not VarIsEmpty(cnn);
　　if Result then
　　begin
　　if cnn.State <> adStateClosed then cnn.Close;
　　cnn.ConnectionString :=
　　\’Provider=SQLOLEDB.1;Persist Security Info=True;Initial Catalog=\’ +
　　db + \’;Data Source=\’ + host + \’;Connect Timeout=5;\’ +
　　\’Use Procedure for Prepare=1\’;
　　try
　　cnn.Open(cnn.ConnectionString, usr, pwd, -1);
　　except
　　Result := False;
　　end;
　　end;
　　end;
　　function ExecSQL(cnn, rst: OleVariant; const sql: string): Boolean;
　　begin
　　Result := not (VarIsEmpty(cnn) or VarIsEmpty(rst)) and (cnn.State = adStateOpen);
　　if Result then
　　begin
　　if rst.State <> adStateClosed then rst.Close;
　　try
　　rst.Open(sql, cnn, adOpenStatic, adLockOptimistic, adCmdText);
　　except
　　Result := False;
　　end;
　　end;
　　end;
　　function ExecSQLA(cnn, cmd: OleVariant; const sql: string): Boolean;
　　begin
　　Result := not (VarIsEmpty(cnn) or VarIsEmpty(cmd)) and (cnn.State = adStateOpen);
　　if Result then来源