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.NET Forum / ASP.NET / General / December 2007What used to be simple is now simply confusing
Yes, a newbie here. Though I am making progress, slowly, I am also getting more and more confused. With ASP, when I wanted to do something as trivial as updating a visitor counter, I connected to a database, executed a SQL command to read the current value of a field into a recordset, updated the value by adding 1 and writing the field back to the table, closed and got rid of the connection and recordset. I had no concerns about how to get or use the information read, or manipulate it. Now I am confronted with issues such as whether or not to use a connected or disconnected database access. Do I really need to build a dataadapter and in-memory table for such a trivial function? Do I really need to be concerned about data binding? Do I really need to use a databound control at all? Will someone please post the minimum ASP.NET instructions to perform this trivial function for me? I suspect that under ASP.NET it is just as trivial as it was under ASP, but as I said earlier, what used to be simple is now simply confusing. Thank you. > Yes, a newbie here. > [quoted text clipped - 23 lines] > > Thank you. SqlConnection conn = new SqlConnection("YourConnectionString"); SqlCommand cmd = new SqlCommand("update MyTable set UserCounter = UserCounter + 1", conn); using (conn) { conn.Open(); cmd.ExecuteNonQuery(); } Amazingly simple when you step away from the details. That accomplished 90% of what I need. Thank you! I assume you still must close or dispose of the connection. All that I need now is to know how to gain access to the new value to set the text value of a label. Can I get that value without having to re-read the field? > SqlConnection conn = new SqlConnection("YourConnectionString"); > SqlCommand cmd = new SqlCommand("update MyTable set UserCounter = [quoted text clipped - 4 lines] > cmd.ExecuteNonQuery(); > } The "using" statement automatically disposes of the connection (which also closes it). You can explicitly call "conn.Close();" if it makes you feel better. :) You'll need another command and a DataReader to get the new value. // Goes right after "ExecuteNonQuery". SqlCommand scmd = new SqlCommand("select UserCounter from MyTable", conn); SqlDataReader dr = scmd.ExecuteReader(); if (dr.Read()) Label2.Text = dr.GetString(0); > Amazingly simple when you step away from the details. That accomplished > 90% [quoted text clipped - 14 lines] >> cmd.ExecuteNonQuery(); >> } Note also that the "old" way you were also executing 2 statements - 1 to read then 1 to update. Now we're still executing 2 statements, but we're doing the update first then the read. This is "safer" because the DB handles concurrency issues for us. > The "using" statement automatically disposes of the connection (which also > closes it). You can explicitly call "conn.Close();" if it makes you feel [quoted text clipped - 26 lines] >>> cmd.ExecuteNonQuery(); >>> } Scott, You are amazingly generous with your help. Again, thank you! > Note also that the "old" way you were also executing 2 statements - 1 to > read then 1 to update. Now we're still executing 2 statements, but we're [quoted text clipped - 31 lines] > >>> cmd.ExecuteNonQuery(); > >>> } Hi, To make some additions... If you still insist on using only one command, you can execute both queries at once and you can get the returning value using "ExecuteScalar" method of the SqlCommand class. Just simple changes to what Scott wrote. I am just now sure about if you need "+1" in second SQL statement, I haven't executed the code but you still may need to save or remove it. int currentCounter = 0; SqlConnection conn = new SqlConnection("YourConnectionString"); SqlCommand cmd = new SqlCommand("update MyTable set UserCounter = UserCounter + 1; Select UserCounter + 1 from MyTable;", conn); using (conn) { conn.Open(); currentCounter = cmd.ExecuteScalar(); }  SignatureAll the best, Coskun SUNALI MVP ASP/ASP.NET http://sunali.com > Scott, > [quoted text clipped - 42 lines] >> >>> cmd.ExecuteNonQuery(); >> >>> } I am just wondering: How can you guarantee that no one else updates the UserCounter in the table before you read the UserCounter LVP > Hi, > [quoted text clipped - 62 lines] >>> >>> cmd.ExecuteNonQuery(); >>> >>> } What I mean is between your update and your read Update ctr = ctr + 1 in table <<<some one else updates it again>>> you read it. > I am just wondering: > How can you guarantee that no one else updates the UserCounter in the [quoted text clipped - 70 lines] >>>> >>> cmd.ExecuteNonQuery(); >>>> >>> } Hi, I am sorry but I don't understand the problem that I will have if someone else updates the table before my read. Current Value = 2 I visited web site { Counter incremented by 1; Someone else visited web site { Counter incremented by 1; } } I got the response: 4; Someone else also got the response 4; So actually the result is even better because I would always like to be sure that I have the most correct value which is 4 here in this case, instead of 3 because someone else also visited the page at the given time. And just because I want to remind you; what is being discused within this topic is not the best practice to have an user counter but having an user counter as much as simple. SignatureAll the best, Coskun SUNALI MVP ASP/ASP.NET http://sunali.com > What I mean is between your update and your read > [quoted text clipped - 78 lines] >>>>> >>> cmd.ExecuteNonQuery(); >>>>> >>> } Okay, I miss-understood the requirements. LVP: > Hi, > [quoted text clipped - 103 lines] >>>>>> >>> cmd.ExecuteNonQuery(); >>>>>> >>> } The process doesn't need to be that much different than what you are doing now albeit that some of the object have changed. You still need a connection to the database and you can then just execute an update statement to modify the db value. This is not a job for DataAdapters and DataSets (disconnected data). > Yes, a newbie here. > [quoted text clipped - 23 lines] > > Thank you. Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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