0
我有问题,此错误:C#错误:“填写:SelectCommand.Connection属性尚未初始化。”
C# Error: “Fill: SelectCommand.Connection property has not been initialized.”
我lloked奥尔其他线程,但人民有它建立了自己的客户有点不同,它没有帮助。 我不知道,为什么这个错误显示。我想它的错误在SelectOsoba
。 我需要在DataGridView中显示数据。
我的代码是:
class Vrstva
{
public static SqlConnection myConnection;
public static string connstr;
static DataTable t;
public static void createConnect1()
{
connstr = ConfigurationSettings.AppSettings["local1"];
Vrstva.myConnection = new SqlConnection(connstr);
}
public static void createConnect2()
{
connstr = ConfigurationSettings.AppSettings["local2"];
Vrstva.myConnection = new SqlConnection(connstr);
}
public static void createConnect3()
{
connstr = ConfigurationSettings.AppSettings["local3"];
Vrstva.myConnection = new SqlConnection(connstr);
}
public static void openConn()
{
Vrstva.myConnection.Open();
}
public static void closeConn()
{
Vrstva.myConnection.Close();
}
public static SqlDataAdapter Query(string command)
{
return new SqlDataAdapter(command, Vrstva.myConnection);
}
public static void NonQuery(string command)
{
SqlCommand Command = new SqlCommand(command, Vrstva.myConnection);
Command.ExecuteNonQuery();
}
public static bool login1(string login, string password)
{
string login1 = ConfigurationSettings.AppSettings["login1"];
string password1 = ConfigurationSettings.AppSettings["password1"];
if (login == login1 && password == password1)
{
return true;
}
return false;
}
public static bool login2(string login, string password)
{
string login1 = ConfigurationSettings.AppSettings["login2"];
string password1 = ConfigurationSettings.AppSettings["password2"];
if (login == login1 && password == password1)
{
return true;
}
return false;
}
public static bool login3(string login, string password)
{
string login1 = ConfigurationSettings.AppSettings["login3"];
string password1 = ConfigurationSettings.AppSettings["password3"];
if (login == login1 && password == password1)
{
return true;
}
return false;
}
////vypis tabulku prislusniku
public static DataTable SelectOsoba()
{
t = new DataTable();
Query("Select * from Osoba;").Fill(t);
return t;
}
//Insert
public static void PridejOsoba(string Jmeno, string Prijmeni, string Povolani, int Poc_Det)
{
NonQuery("Insert into Osoba(Jmeno,Prijmeni,Povolani,Poc_Det) values('" + Jmeno + "','" + Prijmeni + "','" + Povolani + "','" + Poc_Det + "');");
}
}
除了这是一个非常糟糕的包装数据库操作的方式(一切都是静态的!Yu!什么样的程序将使用它?),你可能还没有创建连接。我不知道,因为你没有显示调用代码,但这就是我所猜测的。 –