ASP.NET MVC「System.IndexOutOfRangeException：在位置0沒有行」。當試圖從表中獲取數據時

Question

namespace PayrollSystem.Models 
{ 
    public class FormAddEmployee 
    { 
     public string FirstName { set; get; } 
     public string LastName { set; get; } 
     public decimal PayRate { set; get; } 
     public DateTime StartDate { set; get; } 
     public DateTime EndDate { set; get; } 

     private string m_connectionString; 

     public void Connect(string server, string database) 
     { 
      m_connectionString = string.Format("Data Source ='{0}'; Initial Catalog = {1}; Integrated Security=SSPI", server, database); 
     } 

     public void SaveEmployee() 
     { 
      var commandText = string.Format("INSERT INTO Personnel (FirstName, LastName, PayRate, StartDate, EndDate) VALUES ('{0}', '{1}', {2}, '{3}', '{4}')", FirstName, LastName, PayRate, StartDate, EndDate); 

      SQLDataWriter(commandText); 
     } 



     public void GetEmployeeByLastName(string lastName) 
     { 
      var commandText = string.Format("SELECT FirstName, LastName, PayRate, StartDate, EndDate FROM Personnel WHERE LastName = '{0}'", LastName); 

      var retValue = SQLDataReader(commandText); 
      var rec = retValue.Rows[0]; 
      FirstName = rec.ItemArray[0].ToString(); 
      LastName = rec.ItemArray[1].ToString(); 
      PayRate = Convert.ToDecimal(rec.ItemArray[2].ToString()); 
      StartDate = Convert.ToDateTime(rec.ItemArray[3].ToString()); 
      EndDate = Convert.ToDateTime(rec.ItemArray[4].ToString()); 

     } 

     public DataTable SQLDataReader(string sqlCmd) 
     { 
      var dataTable = new DataTable(); 
      using (var con = new SqlConnection(m_connectionString)) 
      { 
       using (var cmd = new SqlCommand(sqlCmd, con) { CommandTimeout = 500 }) 
       { 
        var sqlAdapter = new SqlDataAdapter(cmd); 
        sqlAdapter.Fill(dataTable); 
       } 
      } 

      return dataTable; 

     } 

     public void SQLDataWriter(string sqlCmd) 
     { 
      using (var con = new SqlConnection(m_connectionString)) 
      { 
       con.Open(); 
       try 
       { 
        using (var command = new SqlCommand(sqlCmd, con)) 
        { 
         command.ExecuteNonQuery(); 
        } 
       } 
       catch (Exception ex) 
       { 
        Console.WriteLine(ex); 
       } 
      } 
     } 



    } 

} 

Answer 1

該查詢可能不會返回任何數據。在訪問之前最好檢查一下。

var retValue = SQLDataReader(commandText); 

if(retValue.Rows.Count > 0) 
{ 
      var rec = retValue.Rows[0]; 
      FirstName = rec.ItemArray[0].ToString(); 
      LastName = rec.ItemArray[1].ToString(); 
      PayRate = Convert.ToDecimal(rec.ItemArray[2].ToString()); 
      StartDate = Convert.ToDateTime(rec.ItemArray[3].ToString()); 
      EndDate = Convert.ToDateTime(rec.ItemArray[4].ToString()); 
} 

Answer 2

首先，你應該使用參數化的命令，以保護自己免受SQL注入......在這種情況下，你的索引進行收集，而不是否有任何行檢查值。

而是執行此操作：

if(retValue.Rows.Count > 0) 
{ 
    var rec = retValue.Rows[0]; 
}