class mpublic User GetUserById(int id)
{ SqlCommand command = new SqlCommand("select * from " + _userdb + " where id=@id", _conn);
command.Parameters.Add("@ID", SqlDbType.Int).Value = id;
SqlDataReader dr = null;
try
{
dr = command.ExecuteReader(CommandBehavior.SingleRow);
if (dr.Read())
{
User user = new User();
user.ID = Convert.ToInt32(dr["id"]);
user.UserID = Convert.ToString(dr["UserID"]);
user.UserName = Convert.ToString(dr["UserName"]);
user.UserLoginPass = Convert.ToString(dr["UserLoginPass"]);
return user;
}
return null;
}
finally
{
if (dr != null && !dr.IsClosed)
{
dr.Close();
}
}
}
假设我调用的时候为空记录
会提示未将对象设置到对象的实例c#如何判断啊?
我想在调用的时候判断
如 if(m.GetUserById(100))
如何判断没有此100的User 调用其它处理
而不是提示"未将对象设置到对象的实例"
{ SqlCommand command = new SqlCommand("select * from " + _userdb + " where id=@id", _conn);
command.Parameters.Add("@ID", SqlDbType.Int).Value = id;
SqlDataReader dr = null;
try
{
dr = command.ExecuteReader(CommandBehavior.SingleRow);
if (dr.Read())
{
User user = new User();
user.ID = Convert.ToInt32(dr["id"]);
user.UserID = Convert.ToString(dr["UserID"]);
user.UserName = Convert.ToString(dr["UserName"]);
user.UserLoginPass = Convert.ToString(dr["UserLoginPass"]);
return user;
}
return null;
}
finally
{
if (dr != null && !dr.IsClosed)
{
dr.Close();
}
}
}
假设我调用的时候为空记录
会提示未将对象设置到对象的实例c#如何判断啊?
我想在调用的时候判断
如 if(m.GetUserById(100))
如何判断没有此100的User 调用其它处理
而不是提示"未将对象设置到对象的实例"
{
//对象为NULL do
}
else
{
//对象为不为NULL do
}