c# - SqlDataReader 显示 InvalidCastException(C# Windows 窗体)

Question

SqlConnection sqlConn = new SqlConnection(ConfigurationManager.ConnectionStrings["myDB"].ConnectionString);
sqlConn.Open();
SqlCommand sqlComm = new SqlCommand("SELECT Price FROM Pricing WHERE FoodID = 1", sqlConn);
SqlDataReader r = sqlComm.ExecuteReader();
while (r.Read())
{
    price1 = (float)r["Price"];
}
r.Close(); 
sqlConn.Close();

我得到的 InvalidCastException 错误指向“price1 = (float)r["Price"];”我是 c# 和任何编程语言的新手，请指导我!

Answer 1

假设 Price 是一个 float ，你应该使用 GetFloat相反:

price1 = r.GetFloat(0); // first column