c# - 在 while 循环中返回

Question

我有一个使用数据库的 C# 方法。现在我尝试返回该值，但因为该字符串是在 while 循环中创建的，所以它说它不存在。有没有一种方法可以返回字符串 kampioen 及其在 while read 循环中创建的值？

public string getkampioen(string selecteditem)
{
    using (MySqlConnection connection = new MySqlConnection(connectionString))
    {
        connection.Open();
        string query = ("select * FROM clubs where naam = '" + selecteditem + "'");
        MySqlCommand cmd = new MySqlCommand(query, connection);
        MySqlDataReader Reader = cmd.ExecuteReader();
        while (Reader.Read())
        {
           string kampioen = (string)Reader["aantalkampioenschappen"].ToString();
        }
        return kampioen; 
    }
}

Answer 1

您可以在 while 循环之前声明字符串。

public string getkampioen(string selecteditem)
{
    using (MySqlConnection connection = new MySqlConnection(connectionString))
    {
        connection.Open();
        string query = ("select * FROM clubs where naam = '" + selecteditem + "'");
        MySqlCommand cmd = new MySqlCommand(query, connection);
        MySqlDataReader Reader = cmd.ExecuteReader();
        string kampioen = "";
        while (Reader.Read())
        {
           kampioen = (string)Reader["aantalkampioenschappen"].ToString();
        }
        return kampioen; 
    }
}