嗨,我使用下面的代码来显示按钮。如果查询不返回任何数据
如果查询结果为“0”的知名度真WORKING
如果查询发现,在数据库中的知名度没有数据错误。 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',对不对? –
您正在调用'ExecuteScalar'两次。存储一次这个值,然后运行你的逻辑。 –
嗨马修,谢谢。我是新来的ASP.NET和真正不明白如何存储值 –