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Why is my math not working on my SQL Server database?

I am developing an asp.net web application and I am trying to add a user xp system to it. I have a SQL Server database connected to it and I am trying to make a function that will give 5 experience points to the user.
I queried to the user that is logged in, accessed the user_xp column, and I am trying to add +5 to the old session variable for xp, then send that back into the database to be stored. Here is my code, I am not sure what is wrong with it.
void generateXp()
{
try
{
SqlConnection con = new SqlConnection(strcon);
if (con.State == ConnectionState.Closed)
{
con.Open();
}
SqlCommand cmd = new SqlCommand("UPDATE member_master_tbl SET user_xp = #user_xp WHERE " +
"user_name = '" + Session["username"].ToString().Trim() + "'", con);
int xp = 5;
int current_xp = Convert.ToInt32(Session["user_xp"]);
int new_xp = xp + current_xp;
string new_xp2 = Convert.ToString(new_xp);
cmd.Parameters.AddWithValue("user_xp", new_xp2);
}
catch (Exception ex)
{
}
}

Try renaming the SQL parameter to #user_xp.
cmd.Parameters.AddWithValue("#user_xp", new_xp2);
I don't have an accessible database to test. Also, you need to add the command to execute the query at the end.
cmd.ExecuteNonQuery()
That being said, it's a good practice to learn to separate DB queries to stored procedures or functions.

As others noted, you simply forgot to do a execute non query to run the command that you setup.
However, you can write things this way. You don't mention or note what the data type the experience points column is - I assumed "int".
So, your code block can be written this way:
using (SqlCommand cmd = new SqlCommand("UPDATE member_master_tbl SET user_xp = #user_xp WHERE user_name = #user",
new SqlConnection(strcon)))
{
cmd.Parameters.Add("#user_xp", SqlDbType.Int).Value = 5 + Session("user_xp");
cmd.Parameters.Add("#user", SqlDbType.NVarChar).Value = Session("username");
cmd.Connection.Open();
cmd.ExecuteNonQuery();
}
note how the command object has a connection object (so we don't need a separate one).
And while several people here "lamented" the string concentration to build the sql and warned about sql injection?
Actually, the introduction of # parameters for both values cleans up the code. So you get nice parameters - nice type checking, and you don't have to remember to add/use/have things like quotes around teh string, but not for numbers.
And I let .net cast the number expression from session() - this also likely is ok.
Also the "using block" also correctly cleans up the command object and also the connection object - so the using block is a good idea here.

UWP connection string

I want to create a connection for my UWP and database. I want the uwp to send a value to the database.
MySql.Data.MySqlClient.MySqlConnection conn;
string myConnectionString;
myConnectionString = "server=127.0.0.1; uid = root;" + "pwd=root;database=test";
try
{
conn = new MySql.Data.MySqlClient.MySqlConnection(myConnectionString);
conn.Open();
}
catch (MySql.Data.MySqlClient.MySqlException ex)
{
}
Is this the correct way to write the connection ? and where do I write this part of the coding at ?
enter image description here
Main page or any of my other page ? (scenario 1-3)

Your content looks right, I would try to use 'localhost' rather than ip.
var myConnection = new MySqlConnection();
myConnection.ConnectionString = "database=test;server=localhost;uid=root;pwd=root";
myConnection.Open();
More info see: https://dev.mysql.com/doc/dev/connector-net/6.10/html/P_MySql_Data_MySqlClient_MySqlConnection_ConnectionString.htm
I would also check here to see if you are providing enough info, which you are. https://www.connectionstrings.com/mysql/
In terms of connecting to the database, it depends. What type of application is this? Typically, database connections are made during the start of the application. If you are using Entity Framework, you'll want your Database Context to manage the connection (which is an entirely different topic).

C# SQLDataAdapter - Not inserting data into DB

Here's what I got: User selects from a checklistbox of database names one they'd like to archive. Switch case in place to catch the selection.
case "userSelection":
sqlAdapter = CreateMyAdapter("dbName", true, sqlconn, null);
sqlAdapter.SelectCommand.CommandText += "";
sqlAdapter.Fill(myDS.tableName);
sqlAdapter.Dispose();
The adapter:
private SqlDataAdapter CreateMyAdapter(string TableName, bool IncludeUpdates, SqlConnection sqlConn, SqlTransaction sqlTran)
{
SqlDataAdapter sqlAdapter = null;
SqlConnection sqlConnArchive = new SqlConnection();
strSQL = "SELECT " + TableName + ".* FROM " + TableName;
sqlAdapter = new SqlDataAdapter(strSQL, sqlConn);
// Right here, I create another sqlConnection that is pointed to
// another datasource.
sqlConnArchive = getThisOtherConnection();
SqlCommand sqlComm;
if (IncludeUpdates)
{
string strInsertSQL = "<insertQuery>";
sqlComm = new SqlCommand(strInsertSQL, sqlConnArchive);
sqlComm.Parameters.Add("#TableID", SqlDbType.Int, 0, "TableID");
// More params here...
sqlAdapter.InsertCommand = sqlComm;
// Update
// Delete
}
}
return sqlAdapter;
The issue:
As you can see sqlConn is the connection that is tied to the SELECT command. And sqlConnArchive is tied to the INSERT. The thought here is that I could select the data from DB_1 if you will, and insert it into DB_2 using the same SQLDataAdapter. But the issue that I'm running into is trying to insert. The select works fine, and at this line sqlAdapter.Fill(myDS.tableName); once fill executes the data is there. But the INSERT isn't working.
A few things:
I tested to see if perhaps SQLDataAdapter couldn't handle multiple datasources/connections, switched things around so it was pointing the the same DB just different tables, and I'm seeing the same results.
I've confirmed that the issue does not reside within the INSERT query.
There are no errors, just steps right over in debug.
I have tried several permutations of .Update() and none of them worked. This project that I've been assigned, throughout the entire thing it appears that .Fill(); is what is submitting the data back to the DB.
I've tested the database side and connectivity is a go. No issues with login, etc etc..
Any help is greatly appreciated.
Please note - I tried to place an even larger emphasis on the word "greatly" but was limited by my toolset. Apparently SOF doesn't support bold, blink, underline, flames, or embedded music.

I think you want ExecuteNonQuery.
var rowsAffected = sqlAdapter.InsertCommand.ExecuteNonQuery();
This executes the statement and then returns the number of rows affected. The Fill method won't run any InsertCommands.

Query not saving to database

I'm trying to save a note into the database by user input but my code isn't saving it to the Database.
I'm planning on checking the user input aswell with functions.
SqlConnection con = database.GetConnection();
SqlCommand command = new SqlCommand("INSERT INTO notities (notities_gebruiker, notities_datum, notities_doeldatum, notities_bericht) values(#notities_gebruiker, #notities_datum, #notities_doeldatum, #notities_bericht)", con);
command.Parameters.AddWithValue("#notities_gebruiker", this.gebruikerid.ToString());
command.Parameters.AddWithValue("#notities_datum", DateTime.Now);
command.Parameters.AddWithValue("#notities_doeldatum", DateTime.ParseExact(this.targetDate.Text, "dd/MM/yyyy", null));
command.Parameters.AddWithValue("#notities_bericht", this.Note.Text);
con.Open();
command.ExecuteNonQuery();
con.Close();
initialiseListBox();
What's happening is that whenever I close my application the database loses it's values saved and goes back to original state. I can add items manually though..
EDIT: It rolls back the rows I have added in via application but I am able to pull the data from the database I saved if I keep it running.

You're forgetting to commit the data you've just inserted. Use the SqlTransaction class to begin a transaction:
SqlTransaction myTransaction = con.BeginTransaction();
command.ExecuteNonQuery();
myTransaction.Commit();
It would be a good idea to make use of the Using statement to make sure your connection, command and transaction are disposed of once the code block has been complete, rather than manually calling Close() methods:
Using (SqlConnection con = database.GetConnection())
{
con.Open();
Using (SqlCommand command = new SqlCommand("sqlhere"))
{
Using (SqlTransaction myTransaction = con.BeginTransaction())
{
//your code here
}
}
}
SqlTransaction class:
http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqltransaction(v=vs.110).aspx
Neat article on using statements:
http://www.codeproject.com/Articles/6564/Understanding-the-using-statement-in-C

Look for a copy of your database containing the data in your bin/debug folder.
Best way to avoid this is to use a full path in your connection string and avoid |DataDirectory| while debugging

.net application's oracle connection timing out

i have the code below trying to do a bulk copy from oracle to SQL server 2005 and it keeps timing out. how can i extend the oracle connection timeout? it seems i can not from what i read on the web.
OracleConnection source = new OracleConnection(GetOracleConnectionString());
source.Open();
SqlConnection dest = new SqlConnection(GetSQLConnectionString() );
dest.Open();
OracleCommand sourceCommand = new OracleCommand(#"select * from table");
using (OracleDataReader dr = sourceCommand.ExecuteReader())
{
using (SqlBulkCopy s = new SqlBulkCopy(dest))
{
s.DestinationTableName = "Defects";
s.NotifyAfter = 100;
s.SqlRowsCopied += new SqlRowsCopiedEventHandler(s_SqlRowsCopied);
s.WriteToServer(dr);
s.Close();
}
}
source.Close();
dest.Close();
here is my oracle connection string:
return "User Id=USER;Password=pass;Data Source=(DESCRIPTION=" +
"(ADDRESS=(PROTOCOL=TCP)(HOST=14.12.7.2)(PORT=1139))" +
"(CONNECT_DATA=(SID=QCTRP1)));";

You can set s.BulkCopyTimeout option

In your connection string, there is a 'Connection Lifetime' and 'Connection Timeout' parameter. You can set it accordingly. See here for the full reference.
BTW, I know you didn't ask this, but have you considered an ETL tool for migrating your DB records (e.g. Informatica, FME, etc.)? While your approach is valid, it isn't going to be very performant since you are hydrating all of the records from one DB to the client and then serializing them to another DB. For small bulk sets, this isn't a big issue, but if you were processing hundreds of thousands of rows, you might want to consider an official ETL tool.