并非所有的代码路径返回一个值问题

Question

我有这样一段代码在一个类（数据库）和我得到

并非所有的路径返回一个值。

任何帮助将非常感激。

public static DataSet DELETE_PDT(String rowid) 
{ 
    SqlConnection con = new SqlConnection(); 
    SqlCommand cmd = new SqlCommand("sp_DELETE_PDT", con); 
    cmd.CommandType = CommandType.StoredProcedure; 
    cmd.Parameters.Add("@rowid", SqlDbType.Int).Value = rowid; 

    con.ConnectionString = ConfigurationManager.ConnectionStrings["WMS"].ConnectionString; 

    try 
    { 
     con.Open(); 
     cmd.ExecuteNonQuery(); 
     cmd.Dispose(); 
     con.Close(); 
    } 
    catch (Exception ex) 
    { 
     throw new Exception("Error while deleting record. Please contact your System Administrator", ex); 
    } 
} 

Answer 1

你的方法应该有一个return value因为你已经宣布它返回Dataset。

例如，

return new Dataset(); 

，如果你不想看到错误消息，改变

public static DataSet DELETE_PDT(String rowid) 
{ 
    // statements 
} 

到

public static void DELETE_PDT(String rowid) 
{ 
    // statements 
} 

更新1

根据您的意见，我会修改它以再次返回字符串值。

public static string DELETE_PDT(String rowid) 
{ 
    using (SqlConnection con = new SqlConnection()) 
    { 
     con.ConnectionString = ConfigurationManager.ConnectionStrings["WMS"].ConnectionString; 
     using (SqlCommand cmd = new SqlCommand("sp_DELETE_PDT", con)) 
     { 
      cmd.CommandType = CommandType.StoredProcedure; 
      cmd.Parameters.Add("@rowid", SqlDbType.Int).Value = rowid; 
      try 
      { 
       if (con.State == ConnectionState.Open) 
       con.Close(); 
       con.Open(); 
       cmd.ExecuteNonQuery(); 
       return "Record has been deleted"; 
      } 
      catch (Exception ex) 
      { 
       return "Error while deleting record. Please contact your System Administrator"; 
      } 
     } 
    } 
} 

Answer 2

你已经声明你的方法返回DataSet ...但你什么都不返回。所以...你需要返回一个DataSet的实例或者改变你的方法签名。

Answer 3

您已声明该方法应该返回DataSet，但它不返回任何内容（这对于该方法所做的操作是合乎逻辑的）。签名更改为：

public static void DELETE_PDT(String rowid) 

---

边注：为了避免异常留下一个未关闭的连接，你可以使用using。它确保命令和连接总是设置无论发生什么情况：

public static void DELETE_PDT(String rowid) { 
    using (SqlConnection con = new SqlConnection()) { 
    con.ConnectionString = ConfigurationManager.ConnectionStrings["WMS"].ConnectionString; 
    using (SqlCommand cmd = new SqlCommand("sp_DELETE_PDT", con)) { 
     cmd.CommandType = CommandType.StoredProcedure; 
     cmd.Parameters.Add("@rowid", SqlDbType.Int).Value = rowid; 
     try { 
     con.Open(); 
     cmd.ExecuteNonQuery(); 
     } catch (Exception ex) { 
     throw new Exception("Error while deleting record. Please contact your System Administrator", ex); 
     } 
    } 
    } 
} 

Answer 4

我已经重构你的代码;试试这个：

public static void DELETE_PDT(String rowid) { 
    using(SqlConnection con = new SqlConnection()) { 
     con.ConnectionString = ConfigurationManager.ConnectionStrings["WMS"].ConnectionString; 
     using(SqlCommand cmd = new SqlCommand("sp_DELETE_PDT", con)) { 
      cmd.CommandType = CommandType.StoredProcedure; 
      cmd.Parameters.Add("@rowid", SqlDbType.Int).Value = rowid; 

      try 
      { 
       con.Open(); 
       cmd.ExecuteNonQuery(); 
       con.Close(); 
      } 
      catch (Exception ex) 
      { 
       throw new Exception("Error while deleting record. Please contact your System Administrator", ex); 
      } 
     } 
    } 
}