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c# SqlDataReader Not Finding Value

My Problem has Been Fixed, My main problem was getting the information from the textbox in the xaml which got erased after that window was closed and another opened. Though the answers did fix my other problems and have made my code much simpler and easier to read. So thank you very much!
So I am Currently working on building a Calendar for a personal project and working on adding events to a Database, this table for Events stores two varchars, and an int (name, description, userid), the userid is a foreign key and is linked to the User Table. When I use the code below to try and pull the userid for the username that the person entered, it tells me that there is no existing value.
using (SqlConnection connection = new SqlConnection())
{
connection.ConnectionString =
"Data Source=calenderserver.database.windows.net;" +
"Initial Catalog=Calender;" +
"User id=*******;" +
"Password=*******;" +
"MultipleActiveResultSets = true";
connection.Open();
SqlCommand com = new SqlCommand("Select UserId from Users Where UserName = #user", connection);
com.Parameters.AddWithValue("#user", UsernameTextBox.Text);
SqlDataReader reader = com.ExecuteReader();
reader.Read();
int userid = reader.GetInt32(1);
messages.Text = "Event Added";
SqlCommand command = new SqlCommand("INSERT INTO [Events] VALUES (#eventname, #eventdesc)", connection);
command.Parameters.AddWithValue("#eventname", name);
command.Parameters.AddWithValue("#eventdesc", description);
command.Parameters.AddWithValue("#userid", userid);
command.ExecuteNonQuery();
reader.Close();
connection.Close();
}
Even though when I run the same command in an actual SQL Query it returns a proper value.
SQL Command
I am completely lost on this and have checked multiple sources and solutions and would really appreciate the help.

You are doing int userid = reader.GetInt32(1); the indexes for the get function are 0 based so you actually need int userid = reader.GetInt32(0); so you get the first column.
That being said, because you are using the first result of the first column you can simplify your code by switching from a data reader to using ExecuteScalar()
SqlCommand com = new SqlCommand("Select UserId from Users Where UserName = #user", connection);
com.Parameters.AddWithValue("#user", UsernameTextBox.Text);
int userid = (int)com.ExecuteScalar();

Try using ExecuteScalar function. Execute scalar returns a single value and I see you only need the user ID.
Take a look at this link .
int userid = (Int32)com.ExecuteScalar();
I Hope it helps!

Indices in GetInt32 are 0-based as per doc, therefore your call should read:
int userid = reader.GetInt32(0);

Change these lines:
SqlDataReader reader = com.ExecuteReader();
reader.Read();
int userid = reader.GetInt32(1);
to:
var userID = com.ExecuteScalar();
Why:
Execute Scalar should be used when your query returns a single value.
Execute Reader returns a collection of data in the form of a DataReader. DataReaders are fast, and you can quickly iterate over them to get the data you need from the database. The connection remains open as long as the datareader is open.
Because you were only getting a single value back from the database, it makes sense to use ExecuteScalar. It's more efficient and too the point.
If you were getting a list of UserID's, then I'd recommend you use a DataReader to iterate through the UserIDs.

c# Update Command to Access Database

I am trying to update data in access table. However, i keep receiving a syntax error when i attempt to update. Below is the code ive compiled. Textbox37 is the one that requires updates.
string constr1;
constr1 = #"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=F:\\Documents\\data.accdb;Jet OLEDB:Database";
string cmdstr = "Update Log(Notes,Status)Values(#a,#b) Where LogIncNum='" + LogInc + "'";
using (OleDbConnection con1 = new OleDbConnection(constr1))
{
using (OleDbCommand com = new OleDbCommand(cmdstr, con1))
{
com.CommandType = CommandType.Text;
com.Parameters.AddWithValue("#a", textBox37.Text);
com.Parameters.AddWithValue("#b", "Active");
con1.Open();
com.ExecuteNonQuery();
}
}

The correct syntax for an update statement is
UPDATE table SET field1=value1, field2=value2 WHERE field3=value3
You are using the wrong syntax hence the syntax error
As a side note, did you forget to use a parameter for the WHERE condition?
It is always correct to use a parameter for every value that you want to include in your query. Just remember to put it in the correct order because OleDb doesn't recognize the parameter by their name, but use a strictly positional order in the Parameters collection, so the first one goes assigned to the first parameter placeholder and so on.

easy way
using (var aq_pension = new System.Web.UI.WebControls.SqlDataSource())
{
aq_pension.ProviderName = "System.Data.OleDb";
aq_pension.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:/stat_tresor/stat_tresor/stat_tresor/db/stat1.mdb";
aq_pension.UpdateCommand = "UPDATE tableaux1 SET nbre=0, montant_mois=0,total=0 WHERE code <>''";
aq_pension.Update();
}

Determining if user login already exists in database?

I am building a web application in asp.net using C#. I have the Form where the user should register and then can login. I am having a problem in making the web app know that the name which the user picks is either "already exists" or not. If it already exists it should not insert the same name and display a message saying "user name already exists". I have tried the SqlDataReader but no luck.
protected void Register_Button_Click(object sender, EventArgs e)
{
SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["BJ_Player_String"].ToString());
SqlCommand cmd = new SqlCommand();
SqlCommand cmd2 = new SqlCommand();
SqlDataReader data_reader;
String name = TextBox2.Text;
String date = TextBox3.Text;
try
{
conn.Open();
cmd = new SqlCommand("Insert into BJ_Player (Player_Name, D_O_B) Values (#Player_name, #D_O_B)", conn);
cmd = new SqlCommand("Select Player_Name from BJ_Player WHERE Player_Name = #Player_name", conn);
cmd.Parameters.Add("#Player_name", SqlDbType.NVarChar).Value = name;
cmd.Parameters.Add("#D_O_B", SqlDbType.Date).Value = date;
cmd.Connection = conn;
data_reader = cmd.ExecuteReader();
cmd.ExecuteNonQuery();
if (data_reader.HasRows)
{
lblPlayerNameExists.Visible = true;
}
else
{
// do nothing
}
}

Make Player_Name unique in database then it will give you exception when you try to insert. You have to use unique constraint.
You have to give command type also and check you assigned both queries to same cmd object

in your code you're inserting data in your DB and then you are examining that the name is the same or not.
first you should search the name in your DB and then if there isn't any record with that name ,you should add your record.

I usually do it in one of two ways:
Create stored procedure that will check for name uniqueness and insert new record if everything is ok. It should return status as numeric code that you will check.
Check for name uniqueness before saving it using as a part of validation process.

Using the merge statement may help with this. Merge performs insert, update, or delete operations on a target table based on the results of a join with a source table.
Basically it inserts when needed, and updates when needed. Often times referred to as an upsert. but it gets the job done.
Here is a link to a site explaining how to use merge. Looks like a good article.
http://www.kodyaz.com/articles/sql-server-2008-t-sql-merge-statement-example.aspx

If you would like to write a model function to do that then
Leave it for ajax check which is pretty similar to the second
method
Issue "Select username from DB-table" to retrieve
usernames then check the username input against them before
displaying a view to report a problem if any or showing a message to
tell the user that "this name is valid", for example.

SQL connection string for microsoft access 2010 .accdb

I am doing a simple login form using winforms and access 2010 database (.accdb) in C#.
I have the following code and it seems that the connection string is wrong. I have tried searching and found that .Jet is for access 07?? but this doesnt seem to work too.
i am an amateur at databases (code referred from msdn). I am having trouble understand which should i use for this example too.
access table name: haha
ID (PK) | password
-----------------------
1 | testing
System.Data.SqlClient.SqlConnection conn = new System.Data.SqlClient.SqlConnection(#"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\BC207\test.accdb");
System.Data.SqlClient.SqlCommand comm = new System.Data.SqlClient.SqlCommand();
comm.CommandText = "SELECT HAHA(*) FROM password";
comm.CommandType = CommandType.Text;
comm.Connection = conn;
conn.Open();
Object returnValue = comm.ExecuteScalar();
conn.Close();
MessageBox.Show((string)returnValue);
edited: the table's name is password, and the field that i want to get the value is ID.
SQL statement i wrote it as : SELECT ID FROM password
and yes, only one record in only one field in the table as the primary key.
anyway the problem is that the program hangs upon execution on the first line
-> Keyword not supported: 'provider'.
so i figured that I have a wrong connection string..

For Acces databases (.mdb, .accdb, etc...), you want to use OleDbConnection, not SqlConnection (SQL Server), like this:
conn = new System.Data.OleDb.OleDbConnection(#"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\BC207\test.accdb")

Edit: as pointed out, for access OleDbConnection should be used, not SqlConnection...
you can use a much more compact way and also be sure connection is closed and disposed in any possible case even when exceptions are thrown, by using the using statements:
your query text was also, probably wrong as others have suggested...
using (var conn = new OleDbConnection(#"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\BC207\test.accdb"))
using (var comm = conn.CreateCommand())
{
comm.CommandText = "SELECT password FROM HAHA";
comm.CommandType = CommandType.Text;
conn.Open();
var returnValue = comm.ExecuteScalar();
MessageBox.Show(returnValue.ToString());
}
Edit: are you sure the table HAHA only contains one row? Because the ExecuteScalar returns only one value, if you want to get 1 column but from many records you could use a DataReader or a DataSet...

comm.CommandText = "SELECT HAHA(*) FROM password";
It´s wrong.
"SELECT password FROM HAHA"

Your SQL statement should be,
SELECT * from HAHA
OR
SELECT [Password] From HAHA
EDIT:
You should change the ConnectionString.

How to update a large table using ADO.NET

Ok, so here's the problem I have to solve. I need to write a method in C# that will modify a table in SQL Server 2008. The table could potentially contain millions of records. The modifications include altering the table by adding a new column and then calculating and setting the value of the new field for every row in the table.
Adding the column is not a problem. It's setting the values efficiently that is the issue. I don't want to read in the whole table into a DataTable and then update and commit for obvious reasons. I'm thinking that I would like to use a cursor to iterate over the rows in the table and update them one by one. I haven't done a whole lot of ADO.NET development, but it is my understanding that only read-only server side (firehose) cursors are supported.
So what is the correct way to go about doing something like this (preferably with some sample code in C#)? Stored procedures or other such modifications to the DB are not allowed.

jpgoody,
Here is an example to chew on using the NerdDinner database and some SQLConnection, SQLCommand, and SQLDataReader objects. It adds one day to each of the Event Dates in the Dinners table.
using System;
using System.Data.SqlClient;
namespace NerdDinner
{
public class Class1
{
public void Execute()
{
SqlConnection readerConnection = new SqlConnection(Properties.Settings.Default.ConnectionString);
readerConnection.Open();
SqlCommand cmd = new SqlCommand("SELECT DinnerID, EventDate FROM Dinners", readerConnection);
SqlDataReader reader = cmd.ExecuteReader();
SqlConnection writerConnection = new SqlConnection(Properties.Settings.Default.ConnectionString);
writerConnection.Open();
SqlCommand writerCommand = new SqlCommand("", writerConnection);
while (reader.Read())
{
int DinnerID = reader.GetInt32(0);
DateTime EventDate = reader.GetDateTime(1);
writerCommand.CommandText = "UPDATE Dinners SET EventDate = '" + EventDate.AddDays(1).ToString() + "' WHERE DinnerID = " + DinnerID.ToString();
writerCommand.ExecuteNonQuery();
}
}
}
}

Your problem looks like something that you should be solving using T-SQL and not C#, unless there is some business rule that you are picking up dynamically and calculating the column values T-SQL should be the way to go. Just write a stored procedure or just open up Management studio and write the code to make your changes.
If this does not help then please elaborate on what exactly you want to do to the table, then we can help you figure out if this can be done via T-SQL or not.
[EDIT] you can do something like this
string sql = " USE " + paramDbName;
sql+= " ALTER TABLE XYZ ADD COLUMN " + param1 + " datatype etc, then put semicolon to separate the commands as well"
sql+= " UPDATE XYZ SET Columnx = " + some logic here
cmd.CommandText = sql;
cmd.ExecuteNonQuery();
get this executed on the required instance of Sql Server 2008.
If you have too many lines of text then use StringBuilder.

Here's a suggestion:
You can read data using a DataReader , create a update command for current row and add it to a list of commands.Then run update commands in a transaction.
something like this:
var commands=new List<SqlCommand>();
while(dr.Read())
{
var cmd=new SqlCommand();
cmd.CommandText="Add your command text here";
commands.Add(cmd);
}
using(var cnn=new SqlConnection("Connection String"))
{
IDbTransaction transaction;
try
{
cnn.Open();
transaction=cnn.BeginTransaction();
foreach(var cmd in commands)
{
cmd.Transaction=transaction;
cmd.ExecuteNonQuery();
cmd.Dispose();
}
transaction.Commit();
}
catch(SqlException)
{
if(transaction!=null)
transaction.Rollback();
throw;
}
}