嗨,我使用下面的代碼來顯示按鈕。如果查詢不返回任何數據
如果查詢結果爲「0」的知名度真WORKING
如果查詢發現,在數據庫中的知名度沒有數據錯誤。 NOT WORKING
string insertSql = "SELECT Status from User_friend WHERE (ProfileId1 =
@FriendProfileId) AND (ProfileId = (SELECT ProfileId FROM User_Profile
WHERE UserId = @UserId))";
using (SqlConnection myConnection = new SqlConnection(connectionString))
{
myConnection.Open();
SqlCommand myCommand = new SqlCommand(insertSql, myConnection);
myCommand.Parameters.AddWithValue("@FriendProfileId",
Request.QueryString["ProfileId"]);
myCommand.Parameters.AddWithValue("@UserId", currentUserId);
if (myCommand.ExecuteScalar().ToString() == null)
{
friendRequestSent.Visible = false;
addFriend.Visible = true;
}
else if (myCommand.ExecuteScalar().ToString() == "0")
{
friendRequestSent.Visible = true;
addFriend.Visible = false;
}
}
你得到'NullReferenceException',對不對? –
您正在調用'ExecuteScalar'兩次。存儲一次這個值,然後運行你的邏輯。 –
嗨馬修,謝謝。我是新來的ASP.NET和真正不明白如何存儲值 –