将数据集转换为VB中的字符串

Question

我在编译代码时出错。它说该数据集不能转换为字符串..请帮助我..我已经通过使用SQL存储过程做到了这一点..我必须获取保存在主表中的员工姓名以检索ID，然后ID应检索离开的详细信息从请假细节表。

Public Shared Function GetEmpID(ByVal EmpName As String) As DataSet 
    Dim db As Database = DatabaseFactory.CreateDatabase(HttpContext.Current.Session("CompanyID").ToString) ' TO Get Database Connection 
    Dim dbCommand As DbCommand = db.GetStoredProcCommand("spRetrieveEmpID") ' Stored Procedure to Execute 
    db.AddInParameter(dbCommand, "EmployeeName", DbType.String, EmpName) ' Parameter for Stored Procedure 
    Return db.ExecuteDataSet(dbCommand) ' Execute Stored Procedure 
End Function 

Public Shared Function EmpLeaveDetails(ByVal EmployeeID As String) As DataSet 
    Dim db As Database = DatabaseFactory.CreateDatabase(HttpContext.Current.Session("CompanyID").ToString) ' TO Get Database Connection 
    Dim dbCommand As DbCommand = db.GetStoredProcCommand("spHRLeaveEntitlement") ' Stored Procedure to Execute 
    db.AddInParameter(dbCommand, "EmployeeID", DbType.String, EmployeeID) ' Parameter for Stored Procedure 
    Return db.ExecuteDataSet(dbCommand) ' Execute Stored Procedure 
End Function 

这是我leave.aspx.vb码

Private Sub ddlEmpName_SelectedIndexChanged(ByVal sender As Object, ByVal e As Telerik.Web.UI.RadComboBoxSelectedIndexChangedEventArgs) Handles ddlEmpName.SelectedIndexChanged 

    EmployeeID = TESTING.GetEmpID(ddlEmpName.Text) 

    If ds.Tables(0).Rows.Count > 0 Then 
     dgLeaveDetails.DataSource = ds 
     dgLeaveDetails.DataBind() 
    End If 

    ds1 = TESTING.EmpLeaveDetails(EmployeeID) 
    dgLeaveDetails.DataSource = ds1 

    ddlEmpName.SelectedIndex = -1 
    dgLeaveDetails.Rebind() 

End Sub 

Answer 1

线

EmployeeID = TESTING.GetEmpID(ddlEmpName.Text) 

貌似这个问题给我。

你应该使用：

Dim dst As Dataset = TESTING.GetEmpID(ddlEmpName.Text) 
EmployeeID = CStr(dst.Tables(0).Rows(0).Item("EmployeeID")) 

Answer 2

要设置EmployeeID，像这样：

EmployeeID = TESTING.GetEmpID(ddlEmpName.Text) 

的GetEmpID方法返回一个DataSet对象。因此，EmployeeID引用了DataSet，而不是等于单个ID值。以后，您尝试通过EmployeeID到EmpLeaveDetails方法是这样的：

ds1 = TESTING.EmpLeaveDetails(EmployeeID) 

然而，EmpLeaveDetails方法采用String作为参数。因此，您正在尝试将DataSet传递给期望String的方法。由于DataSet对象不能自动转换为String类型，因此编译器会提供该错误。

要解决该问题，您需要让GetEmpID返回一个字符串，否则在将其传递给EmpLeaveDetails方法之前，您需要从DataSet中检索单个字符串值。