c# - 如何在插入gridview之前知道一行的值？

Question

我有这个查询：

SELECT COUNT(date) FROM patients WHERE date= 2012/02/23

如果那个 COUNT 返回 10，就会有一个警告告诉用户它不能接受更多的访问。我该如何验证？我怎么知道？在php中我只需要这样做：

<?php

$QUERY = "SELECT COUNT(date) AS count_results FROM patients WHERE date= 2012/02/23";
$execute_query = $CONEXION ->prepare($query);
$execute_query->execute();
$results = execute_query->fetch(PDO::FETCH_ASSOC);

if(results['count_results ']==10)
{
echo "Cannot accept know visit.";
}else{
echo "Ok";
}
?>

但我不知道如何在 ASP.NET C# 中做到这一点。帮助？？

Answer 1

如果您正在验证登录用户，请在 page_load 事件中执行检查。或者，如果您需要根据您尝试插入的用户值进行验证，请使用 button_click 事件来插入记录。

SqlCommand cmdEvent = new SqlCommand("SELECT COUNT(date) FROM patients WHERE date= '2012/02/23'", yourSqlConnection);
object myCount;
if (yourSqlConnection.State == ConnectionState.Closed){ yourSqlConnection.Open(); }
myCount = cmdEvent.ExecuteScalar();
if (yourSqlConnection.State == ConnectionState.Open){ yourSqlConnection.Close(); }

if (myCount != null)
{
  if ((int)myCount >= 10)
  {
    // Logic here e.g myLabel.Text = "You have reached your maximum of 10 visits!";
    return;
  }
}