以下判断数据库类型并创建相应的对象

 public static DataBase CreateData(string ConnectionString, string ProviderName)
        {
            
            if (ProviderName.ToUpper().Contains("OLEDB"))
            {
                OleDbDataAdapter oledbda = new OleDbDataAdapter();
                oledbda.SelectCommand = new OleDbCommand();
                oledbda.SelectCommand.Connection = new OleDbConnection(ConnectionString);
                return new DataBase(oledbda);
            }
            if (ProviderName.ToUpper().Contains("SQL"))
            {
                SqlDataAdapter sqlda = new SqlDataAdapter();
                sqlda.SelectCommand = new SqlCommand();
                sqlda.SelectCommand.Connection = new SqlConnection(ConnectionString);
                return new DataBase(sqlda);
            }
            if (ProviderName.ToUpper().Contains("ODBC"))
            {
                OdbcDataAdapter odbcda = new OdbcDataAdapter();
                odbcda.SelectCommand = new OdbcCommand();
                odbcda.SelectCommand.Connection = new OdbcConnection(ConnectionString);
                return new DataBase(odbcda);
            }
            return null;
        }