删除外键

Question

我试图删除表NatureCharge外键引用了粉彩的表的主键，因为我需要在彩

删除多行删除多行，它的工作原理，但与问题删除行中NatureCharge 中的表看起来像
的代码：与线

private void DeleteFamBtn_Click(object sender, EventArgs e) 
    { 
     List<DataGridViewRow> selectedRows = (from row in DataGridViewFamille.Rows.Cast<DataGridViewRow>() 
               where Convert.ToBoolean(row.Cells["checkBoxColumn"].Value) == true 
               select row).ToList(); 


     if (MessageBox.Show(string.Format("Do you want to delete {0} rows?", selectedRows.Count), "Confirmation", MessageBoxButtons.YesNo) == DialogResult.Yes) 
     { 
      //delete Nature de Charge before delete Famille 
      foreach (DataGridViewRow row in selectedRows) 
      { 
       try 
       { 
        using (SqlConnection con = new SqlConnection(connstring)) 
        { 
         con.Open(); 
         using (SqlCommand command = new SqlCommand("DELETE NatureCharge FROM NatureCharge n INNER JOIN Famille f on n.IdFam = f.IdFam WHERE IdNat = @IdNat", con)) 
         { 
          command.ExecuteNonQuery(); 
         } 
         con.Close(); 
        } 
       } 
       catch (SystemException ex) 
       { 
        MessageBox.Show(string.Format("An error occurred: {0}", ex.Message)); 
       } 
      } 

      //Delete Famille 
      foreach (DataGridViewRow row in selectedRows) 
      { 
       using (SqlConnection con = new SqlConnection(connstring)) 
       { 
        using (SqlCommand cmd = new SqlCommand("DELETE FROM Famille WHERE IdFam = @IdFam", con)) 
        { 
         cmd.CommandType = CommandType.Text; 
         cmd.Parameters.AddWithValue("@IdFam", row.Cells["IdFam"].Value); 
         con.Open(); 
         cmd.ExecuteNonQuery(); 
         con.Close(); 
        } 
       } 
      } 

一个错误显示（这是彩部分）

cmd.ExecuteNonQuery（）;

附加信息：DELETE语句与参考约束“FK_NatureCharge_Famille”冲突。冲突发生在数据库“Tresorerie”，表“dbo.NatureCharge”，列'IdFam'。

Answer 1

你忘了加上@IdNat参数在这里：

using (SqlCommand command = new SqlCommand("DELETE NatureCharge FROM NatureCharge n INNER JOIN Famille f on n.IdFam = f.IdFam WHERE IdNat = @IdNat", con)) 
{ 
    // you haven't added the @IdNat parameter 
    command.ExecuteNonQuery(); 
} 

，如果你收拾你的代码这将更加明显。

string sql = "DELETE NatureCharge 
       FROM NatureCharge n 
       INNER JOIN Famille f on n.IdFam = f.IdFam 
       WHERE IdNat = @IdNat"; 
          ^^^^^^ 
using (SqlCommand command = new SqlCommand(sql, con)) 
{ 
    // you haven't added the @IdNat parameter 
    command.ExecuteNonQuery(); 
}