返回多個sqlcommands

我得到，我們可以使用using在sqlconnection有多個命令。返回多個sqlcommands

像這樣：

using (SqlConnection connection = new SqlConnection(connectionString)) 
{ 
    connection.Open(); 
    using (SqlCommand command1 = new SqlCommand(commandText1, connection)) 
    { 
    } 
    using (SqlCommand command2 = new SqlCommand(commandText2, connection)) 
    { 
    } 
    // etc 
}

然而，如果該using是在返回讀者投的方法？

像這樣：

public IEnumerable<LocationInfo> GetData() 
{   
    using (var connection = new SqlConnection(ConfigurationManager.ConnectionStrings["Database"].ConnectionString)) 
    { 
     //connection.Close(); 
     connection.Open(); 
     using (SqlCommand command = new SqlCommand(@"SELECT .... ", connection)) 
     {   
      command.Notification = null; 
      SqlDependency dependency = new SqlDependency(command); 
      dependency.OnChange += new OnChangeEventHandler(dependency_OnChange); 

      if (connection.State == ConnectionState.Closed) 
      { connection.Open(); } 
      using (var reader = command.ExecuteReader()) 
      { 
       return reader.Cast<IDataRecord>().Select(x => new LocationInfo()       
       { 
        Names = x.GetString(2), 
        Values = Math.Round(x.GetDouble(7), 2).ToString("#,##0.00"), 
        ValuesDouble = x.GetDouble(7), 
        Values2 = Math.Round(x.GetDecimal(9), 2).ToString("#,##0.00"), 
        ValuesDouble2 = x.GetDecimal(9), 
        truckDelivery=x.GetDecimal(3), 
        truckIdle = x.GetDecimal(4), 
        truckRepair = x.GetDecimal(5), 
        truckReady = x.GetDecimal(6), 
        presentEmp=x.GetInt32(11), 
        absentEmp = x.GetInt32(12), 
        ondutyEmp = x.GetInt32(13), 
       }).ToList(); 
      } 
      /* I tried this but it just got ignored 
      using (var reader2 = command.ExecuteReader()) 
      { 
       reader2.NextResult(); 
       return reader2.Cast<IDataRecord>().Select(x => new LocationInfo() 
       { 
        SumVol = x.GetString(0)  
       }).ToList(); 
      }*/ 
     } 
    } 
}

請幫助我。我的第二個using一直被忽視，不要認爲我知道什麼，因爲我是新手。先謝謝你。

來源

2016-12-21 MVCNoob

您錯過了對reader.Read（）的調用。目前還不清楚這個代碼是僅僅在記錄還是一組記錄中檢索。在後一種情況下，你需要一個循環 – Steve

除了Steve的建議，第二個'using'被忽略，因爲在第一個'using'塊中有一個'return'，這可能是這個對象從返回的原因第一個'using'塊和下面的代碼被忽略。 – Aamir

它正在做一個從數據庫中檢索數據的循環，並且也用於像這樣的值控制器：public class ValuesController：ApiController { LocationInfoRepository objRepo = new LocationInfoRepository（）; // GET api/values public IEnumerable Get（） { return objRepo.GetData（）; } }我知道第二個使用無知的原因是因爲return語句，我如何修改它以便我修復它。謝謝你的幫助@Steve – MVCNoob

您需要讀取由ExecuteReader獲取的SqlDataReader指向的記錄。在列表中累積您的LocationInfo，並在完成循環讀取器時返回它們。

public IEnumerable<LocationInfo> GetData() 
{ 
    List<LocationInfo> locations = new List<LocationInfo>(); 
    using (var connection = new SqlConnection(ConfigurationManager.ConnectionStrings["Database"].ConnectionString)) 
    using (SqlCommand command = new SqlCommand(@"SELECT .... ", connection)) 
    { 
     connection.Open(); 
     using (var reader = command.ExecuteReader()) 
     { 
      while(reader.Read()) 
      { 
       LocationInfo x = new LocationInfo() 
       { 
        Names = x.GetString(2), 
        Values = Math.Round(x.GetDouble(7), 2).ToString("#,##0.00"), 
        ValuesDouble = x.GetDouble(7), 
        Values2 = Math.Round(x.GetDecimal(9), 2).ToString("#,##0.00"), 
        ValuesDouble2 = x.GetDecimal(9), 
        truckDelivery=x.GetDecimal(3), 
        truckIdle = x.GetDecimal(4), 
        truckRepair = x.GetDecimal(5), 
        truckReady = x.GetDecimal(6), 
        presentEmp=x.GetInt32(11), 
        absentEmp = x.GetInt32(12), 
        ondutyEmp = x.GetInt32(13), 
       }; 
       locations.Add(x); 
      } 
     } 
    } 
    return locations; 

}

來源

2016-12-21 09:14:00 Steve

好的，您可以在您的情況下將兩個結果集的結果合併到一個對象中。

public IEnumerable<LocationInfo> GetData() 
{ 
     List<LocationInfo> locations = new List<LocationInfo>(); 
     using (var connection = new SqlConnection(ConfigurationManager.ConnectionStrings["Database"].ConnectionString)) 
     using (SqlCommand command = new SqlCommand(@"SELECT .... ", connection)) 
     { 
      connection.Open(); 

      using (var reader = command.ExecuteReader()) 
      { 
       LocationInfo x = new LocationInfo(); 
       while(reader.Read()) 
       { 

        { 
         x.Names = reader.GetString(2), 
         x.Values=Math.Round(reader.GetDouble(7),2).ToString("#,##0.00"), 
         x.ValuesDouble = reader.GetDouble(7), 
         Values2 = Math.Round(reader.GetDecimal(9), 2).ToString("#,##0.00"), 
         x.ValuesDouble2 = reader.GetDecimal(9), 
         x.truckDelivery=reader.GetDecimal(3), 
         x.truckIdle = reader.GetDecimal(4), 
         x.truckRepair = reader.GetDecimal(5), 
         x.truckReady = reader.GetDecimal(6), 
         x.presentEmp=reader.GetInt32(11), 
         x.absentEmp = reader.GetInt32(12), 
         x.ondutyEmp = reader.GetInt32(13), 
        }; 

       } 
       if(reader.NextResult()) 
       { 
       while (reader.Read()) 
       { 
        x.SumVol=reader.GetString(0); 
       } 
       } 
       locations.Add(x); 
      } 
     } 
     return locations; 
}

來源

2016-12-21 10:35:48 Aamir

返回多個sqlcommands

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