Question

for (int i = 0; i <= GridView1.Rows.Count - 1; i++)
{
    string toemail = GridView1.Rows[i].Cells[2].Text;
    string FID1 = GridView1.Rows[i].Cells[0].Text;
    GridViewRow row = GridView1.Rows[i];
    CheckBox Ckbox = (CheckBox)row.FindControl("CheckBoxMark1");
    if (Ckbox.Checked == true)
    {
        sendMail(toemail);

        //ClientScript.RegisterStartupScript(Page.GetType(), "validation", "<script language='javascript'>alert('Email send Succesfully')</script>");
        ClientScript.RegisterStartupScript(Page.GetType(), "validation", "<script language='javascript'>alert('Email sent Succesfully on " + test + "')</script>");

        cn1.Open();
       //cmd4.CommandText = "Insert into TrackingFaculty_det  (EmailsentDate)  values (@EmailsentDate) WHERE FID=@FID";
       cmd4.CommandText = "update TrackingFaculty_det SET EmailsentDate=@Email WHERE FID=@FID  ";
       cmd4.CommandType = CommandType.Text;
       cmd4.Connection = cn1;

       cmd4.Parameters.Add("@Email", SqlDbType.DateTime, 8);
       cmd4.Parameters["@Email"].Value = sdt;
       cmd4.Parameters.Add("@FID",SqlDbType.VarChar,10);
       cmd4.Parameters["@FID"].Value = FID1;
       cmd4.ExecuteNonQuery();
       cn1.Close();
    }
}

//这是c#代码的一部分以及asp.net

如果for loop执行updation，database for loop应该在update中完成，The variable name '@Email' has already been declared. Variable names must be unique within a query batch or stored procedure.执行{{1}}多次{{1}}次问题，则会出现问题会给出{{1}}的错误。对此有什么解决方法吗？

Answer 1

只需将循环的不变部分移到循环外部即可。这意味着，SqlCommand的初始化，连接的打开以及参数集合的创建然后在循环内部只需更改参数值并执行。（这总是比在循环内重新创建相同的参数列表更快）

   SqlCommand cmd4 = new SqlCommand("update TrackingFaculty_det " + 
                                    "SET EmailsentDate=@Email WHERE FID=@FID", cn1);
   cn1.Open();
   cmd4.Parameters.Add("@Email", SqlDbType.DateTime, 8);
   cmd4.Parameters.Add("@FID",SqlDbType.VarChar,10);
   for (int i = 0; i <= GridView1.Rows.Count - 1; i++)
   {
       .....
       if (Ckbox.Checked == true)
       {
          ....
          cmd4.Parameters["@Email"].Value = sdt;
          cmd4.Parameters["@FID"].Value = FID1;
          cmd4.ExecuteNonQuery();
       }
   }
   cn1.Close();

Answer 2

尝试清除命令参数 -

cmd4.Parameters.Clear();

然后添加参数

cmd4.Parameters.Add("@Email", SqlDbType.DateTime, 8);

所以你的最终代码是 -

cmd4.Parameters.Clear();  //  <- Just add this line
cmd4.Parameters.Add("@Email", SqlDbType.DateTime, 8);

Answer 3

每次都应该刷新

cmd4对象。

  cmd4.Parameters.Add("@Email", SqlDbType.DateTime, 8);
  cmd4.Parameters["@Email"].Value = sdt;
  cmd4.Parameters.Add("@FID",SqlDbType.VarChar,10);
  cmd4.Parameters["@FID"].Value = FID1;

您将相同的参数多次添加到“cmd4”

的参数列表中

在再次添加相同参数之前清除参数

cmd4.Parameters.Clear();

Answer 4

检查Run Stored Procedure with table data as parameter

或者第二个是使用下面的示例创建字符串，并在sql server

中创建exec（字符串）

sqlstr= "update TrackingFaculty_det SET EmailsentDate=2@2.com WHERE FID=1; update TrackingFaculty_det SET EmailsentDate=1@1.com WHERE FID=@FID ;pdate TrackingFaculty_det SET EmailsentDate=2@2.com WHERE FID=1;"

在for循环中执行sql查询

4 个答案: