我如何重构这两种方法

Question

您好，我有两个方法，如和三个以上的方法（在这个问题上没有提及）..

我如何重构这些的..

方法1：

public DataTable GetVisits(System.DateTime startdate , System.DateTime enddate) 
    { 


     const string sql = @"SELECT CONCAT(UPPER(SUBSTRING(visit_Status, 1, 1)), SUBSTRING(visit_Status FROM 2)) as Status, COUNT('x') AS Visits 
           FROM visits 
           WHERE visit_Date BETWEEN @startdate AND @enddate 
           GROUP BY visit_Status"; 

     var tblvisits = new DataTable(); 

     using (var conn = new MySql.Data.MySqlClient.MySqlConnection(connectionstring)) 
     { 
      conn.Open(); 

      var cmd = new MySql.Data.MySqlClient.MySqlCommand(sql, conn); 


      var ds = new DataSet(); 

      var parameter = new MySql.Data.MySqlClient.MySqlParameter("@startdate", MySql.Data.MySqlClient.MySqlDbType.DateTime); 
      parameter.Direction = ParameterDirection.Input; 
      parameter.Value = startdate.ToString(dateformat); 
      cmd.Parameters.Add(parameter); 

      var parameter2 = new MySql.Data.MySqlClient.MySqlParameter("@enddate", MySql.Data.MySqlClient.MySqlDbType.DateTime); 
      parameter2.Direction = ParameterDirection.Input; 
      parameter2.Value = enddate.ToString(dateformat); 
      cmd.Parameters.Add(parameter2); 

      var da = new MySql.Data.MySqlClient.MySqlDataAdapter(cmd); 

      da.Fill(ds); 
      try 
      { 
       tblvisits = ds.Tables[0]; 

      } 
      catch 
      { 
       tblvisits = null; 

      } 

     } 
     return tblvisits; 
    } 

方法2：：

 public DataTable sales(System.DateTime startdate, System.DateTime enddate) 
     { 
     const string sql = @"SELECT memberAccTran_Source as Category, sum(memberAccTran_Value) as Value 
           FROM memberacctrans 
           WHERE memberAccTran_DateTime BETWEEN @startdate AND @enddate 
           GROUP BY memberAccTran_Source"; 

     var memacctvalues = new DataTable(); 
     using (var conn = new MySql.Data.MySqlClient.MySqlConnection(connectionstring)) 
     { 
      conn.Open(); 

      var cmd = new MySql.Data.MySqlClient.MySqlCommand(sql, conn); 

      var ds = new DataSet(); 

      var parameter = new MySql.Data.MySqlClient.MySqlParameter("@startdate", MySql.Data.MySqlClient.MySqlDbType.DateTime); 
      parameter.Direction = ParameterDirection.Input; 
      parameter.Value = startdate.ToString(dateformat); 
      cmd.Parameters.Add(parameter); 

      var parameter2 = new MySql.Data.MySqlClient.MySqlParameter("@enddate", MySql.Data.MySqlClient.MySqlDbType.DateTime); 
      parameter2.Direction = ParameterDirection.Input; 
      parameter2.Value = enddate.ToString(dateformat); 
      cmd.Parameters.Add(parameter2); 

      var da = new MySql.Data.MySqlClient.MySqlDataAdapter(cmd); 

      da.Fill(ds); 
      try 
      { 
       memacctvalues = ds.Tables[0]; 

      } 
      catch 
      { 
       memacctvalues = null; 
      } 
     } 
     return memacctvalues;   
    } 

会不会有人有任何想法我怎么可以重构这两种方法

（

我有三个方法更喜欢这一点，但唯一不同的是SQL查询 ）

Answer 1

如果方法的所有风格之间的唯一区别是SQL代码，那么为每个方法创建一个公共方法，并让它们全部调用一个私有方法，该私有方法具有通信在代码中传入正确的sql字符串。

private DataTable PerformQuery(string sql, System.DateTime startdate, System.DateTime enddate) 
{ 
    var tblvisits = new DataTable(); 

    using (var conn = new MySql.Data.MySqlClient.MySqlConnection(connectionstring)) 
    { 
     conn.Open(); 

     var cmd = new MySql.Data.MySqlClient.MySqlCommand(sql, conn); 


     var ds = new DataSet(); 

     var parameter = new MySql.Data.MySqlClient.MySqlParameter("@startdate", MySql.Data.MySqlClient.MySqlDbType.DateTime); 
     parameter.Direction = ParameterDirection.Input; 
     parameter.Value = startdate.ToString(dateformat); 
     cmd.Parameters.Add(parameter); 

     var parameter2 = new MySql.Data.MySqlClient.MySqlParameter("@enddate", MySql.Data.MySqlClient.MySqlDbType.DateTime); 
     parameter2.Direction = ParameterDirection.Input; 
     parameter2.Value = enddate.ToString(dateformat); 
     cmd.Parameters.Add(parameter2); 

     var da = new MySql.Data.MySqlClient.MySqlDataAdapter(cmd); 

     da.Fill(ds); 
     try 
     { 
      tblvisits = ds.Tables[0]; 

     } 
     catch 
     { 
      tblvisits = null; 

     } 

    } 
    return tblvisits; 
} 

然后对公立：

public DataTable Sales(System.DateTime startdate, System.DateTime enddate) 
    { 
    const string sql = @"SELECT memberAccTran_Source as Category, sum(memberAccTran_Value) as Value 
          FROM memberacctrans 
          WHERE memberAccTran_DateTime BETWEEN @startdate AND @enddate 
          GROUP BY memberAccTran_Source"; 

     return PerformQuery(sql, startdate, enddate); 
    } 



    public DataTable GetVisits(System.DateTime startdate , System.DateTime enddate) 
    { 
     const string sql = @"SELECT CONCAT(UPPER(SUBSTRING(visit_Status, 1, 1)), SUBSTRING(visit_Status FROM 2)) as Status, COUNT('x') AS Visits 
           FROM visits 
           WHERE visit_Date BETWEEN @startdate AND @enddate 
           GROUP BY visit_Status"; 
      return PerformQuery(sql, startdate, enddate); 
     } 

，并重复每个人的。正如您似乎表明的那样，假设所有参数都是相同的，唯一的区别是正在运行的SQL。

Answer 2

只需将SQL查询放在方法外并将其作为参数传递。