如何获取数据集值

Question

VB.Net新手，

如何插入或选择数据集值。

cmd = New SqlCommand("Select * from table1", con) 
    ada = New SqlDataAdapter(cmd) 
    ds = New DataSet 
    ada.Fill(ds) 
    cmd = New SqlCommand("Select * from '" & ds.Tables(0) & "' ", con) 
    mydatatable1.Load(dr3) 

它显示'" & ds.Tables(0) & "'错误，我想要得到的数据集值

需要VB.Net代码帮助

Answer 1

你有一个合理的想法的权利，直到你得到的地步您正尝试创建第二个SqlCommand。也就是，一旦你做了填充，你已经有了一个表中的数据。你不会运行另一个选择 - 你已经做到了。您只需引用要在数据集中使用的表格。

如果你想有一个数据表，你会做这样的事情（为VB，见下文）：

SqlDataAdapter myAdapter = new SqlDataAdapter(CommandText, con); 
    DataSet myDataset = new DataSet(); 
    myAdapter.Fill(myDataset, "Table"); // "Table" is just a name, it can be anything. 
    mydatatable1 = myDataset.Tables[0]; // Get the table 

现在，如果你不需要一个DataTable本身，而只是想读从查询，你会使用SqlDataReader：

cmd = new SqlCommand(CommandText, con); 
// One or more params 
cmd.Parameters.AddWithValue("@paramName", Value); 
SqlDataReader nwReader = cmd.ExecuteReader(); 

然后，只需从阅读nwReader：

while (nwReader.Read()) 
{ 
    string field1Val = (string)nwReader["FieldName"]; 
    etc... 
} 

---

更新：我不知道VB，但这里是我认为它会是什么样子：

cmd = New SqlCommand("Select * from table1", con) 
ada = New SqlDataAdapter(cmd) 
ds = New DataSet 
ada.Fill(ds) 
mydatatable1 = ds.Tables(0); 

您可能能够缩短这种摆脱额外的SqlCommand（假设VB支持像C＃这样的SqlDataAdapater语法。

ada = New SqlDataAdapter("Select * from table1", con) 
ds = New DataSet 
ada.Fill(ds) 
mydatatable1 = ds.Tables(0); 

好运...

Answer 2

你可以使用微软企业库制作方便这一进程。这个库是一个处理数据集的强大库。

Answer 3

我想你在找什么是

CMD =新的SqlCommand（ “从选择* '” & ds.Tables（0）。表名 & “'”，CON）

cmd = New SqlCommand("Select * from table1", con) 
ada = New SqlDataAdapter(cmd) 
ds = New DataSet 
ada.Fill(ds) 
cmd = New SqlCommand("Select * from '" & ds.Tables(0).TableName & "' ", con) 
mydatatable1.Load(dr3) 

Answer 4

public async Task<ResponseStatusViewModel> GetAll() 
     { 
      var responseStatusViewModel = new ResponseStatusViewModel(); 
      var connection = new SqlConnection(EmployeeConfig.EmployeeConnectionString); 
      var command = new SqlCommand("usp_GetAllEmployee", connection); 
      command.CommandType = CommandType.StoredProcedure; 

      try 
      { 
       await connection.OpenAsync(); 
       var reader = await command.ExecuteReaderAsync(); 

       var dataSet = new DataSet(); 
       dataSet.Load(reader, LoadOption.OverwriteChanges, new string[] { "Employee" }); 
       reader.Close(); 
       reader.Dispose(); 

       var employees = new List<EmployeeModel>(); 

       if (dataSet.Tables.Count > 0 && dataSet.Tables["Employee"] != null) 
       { 
        var employeeTable = dataSet.Tables["Employee"]; 

        for (int i = 0; i < employeeTable.Rows.Count; i++) 
        { 
         var employeeRow = employeeTable.Rows[i]; 

         employees.Add(new EmployeeModel 
         { 
          EmployeeID = Convert.ToInt32(employeeRow["EmployeeID"]), 
          EmployeeName = Convert.ToString(employeeRow["EmployeeName"]), 
          Address = Convert.ToString(employeeRow["Address"]), 
          GrossSalary = Convert.ToDouble(employeeRow["GrossSalary"]), 
          PF = Convert.ToDouble(employeeRow["PF"]), 
          TotalSalary = Convert.ToDouble(employeeRow["TotalSalary"]) 
         }); 
        } 
       } 
       responseStatusViewModel.Data = employees; 
       command.Dispose(); 
       connection.Dispose(); 

      } 
      catch (Exception ex) 
      { 

       throw ex; 
      } 

      return responseStatusViewModel; 
     }