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OLEDB commands aren't being saved in access database

I'm working in Windows Forms and trying to use OLEDB to connect to an access .accdb file.
I can SELECT data without issue.
I can execute Insert and Create commands with no error.
But when I check the database afterward the data is not showing.
For example, when I create a new Table, the code will say the table was created and if I try to create the table again without closing the Windows Form it will throw an error saying the table already exists, but if I close and restart the program it will let me create the table once more.
Also, if I look into the Access file I wont see the table.
I've tried multiple tests both with Access open and closed. The Connection String is correct as I have made changes to tables in the Access file and they are reflected in the SELECT queries I've sent.
I suspect there must be a setting in Access I must enable for it to autocommit changes. But I haven't found it.
OleDbConnection conn = new OleDbConnection(#"Provider = Microsoft.ACE.OLEDB.12.0; Data Source =Database2.accdb");
string query = "INSERT INTO [TestTable] ([Test_Name], [Test_Number]) VALUES (?, ?)";
try
{
OleDbCommand cmd = new OleDbCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = query;
cmd.Parameters.AddWithValue("Test_Name", list_all_meters[0][0].Name);
cmd.Parameters.AddWithValue("Test_Number", list_all_meters[0][0].Value);
cmd.Connection = conn;
conn.Open();
cmd.ExecuteNonQuery();
conn.Close();
MessageBox.Show("An Item has been successfully added", "Caption", MessageBoxButtons.OKCancel, MessageBoxIcon.Information);
}catch(Exception ex)
{
Debug.WriteLine(ex.Message);
}

Looks like the issue was I had set the Database "Copy to Output Directory" to Copy Always, which overwrote my changes every time I ran the program. Changing it to Copy if Newer fixed the issue.

Data is not showing/updating in the SQLite table when the data is inserted through my C# code

Currently, I have been doing some simple coding related to SQL and C#. I have created this a registration form which will store the data, username and password, in an SQLite database. This is the code that I am currently using:
private void AddLoginInfo(string username, string password)
{
auth = new Authentication();
auth.getConnection();
using (SQLiteConnection con = new SQLiteConnection(auth.connectionstring))
{
SQLiteCommand cmd = new SQLiteCommand();
con.Open();
string que = #"INSERT INTO LoginInfo(Username, Password) VALUES (#username, #password)";
cmd.CommandText = que;
cmd.Connection = con;
cmd.Parameters.Add(new SQLiteParameter("#Username", username));
cmd.Parameters.Add(new SQLiteParameter("#Password", password));
cmd.ExecuteNonQuery();
MessageBox.Show("Account Created!");
}
}
This code currently works and does add to the correct table in the database however whenever a new user is added. The user information can be used to login but it does not show within the table, which is viewed using DB Browser for SQLite.
For example, if I create a new user; 'admin' as the username and 'password' as the password, through the form, I get the message box saying 'Account Created' and I can use that very account to login. However, if I go view that very data in the DB browser the data doesn't show even after refreshing the table.
After doing some digging, I found this and saw that they were using sqlCommand.Parameters.AddWithValue so I tried this within my code:
SQLiteCommand cmd = new SQLiteCommand(#"INSERT INTO LoginInfo(Username, Password) VALUES (#username, #password)", con);
cmd.Parameters.AddWithValue(new SQLiteParameter("#Username", txtBoxUsername.Text));
I tried this and I got a CS7036 error. Then I realised that they had not used the new SQLiteParameter() part and so I removed it cmd.Parameters.AddWithValue("#Username", txtBoxUsername.Text); and tried again but it still wouldn't update in the table but the data could still be used to log in.
I have also found a similar post but no one had answered it.
Now I don't know what to do, so I am asking for your help.

I figured out what was the problem; I was checking the database that was stored in the solution but what I should have checked is the database stored in the ...\bin\debug folder. The database within the folder shows the added data.

Are you retrieving the db file from another system? i.e. Android Emulator or a network location?
Are there any other files in the folder, you are specifically looking for a filename that contains '-wal'. Additional information on SQLite Wal format
the data is actually contained in this other file. DB Browser knows to look for this file. However, if you are downloading the db to your system before you take a look, you are probably not downloading the -wal file as well.
Depending on how you are configuring your SQLite db, the limit by default for checkpoint threshold is 1kb. Until the checkpoint is triggered, the data doesn't get transferred to the main db file. There are ways to manually trigger the checkpoint, see the link I have included above.

Insert Into local database C#

I can't Insert and select from Local database data in C#.
I've read these articles
C# - Writing data in local database
http://msdn.microsoft.com/en-us/library/system.data.sqlserverce.sqlceconnection(v=vs.100).aspx
How to add local database items into textBox using listBox in C#
All the code samples are the same, here's my sample.
SqlCeConnection conn = new SqlCeConnection(#"Data Source=|DataDirectory|\PacjenciDB.sdf");
conn.Open();
SqlCeCommand cmd = conn.CreateCommand();
cmd.CommandText="INSERT INTO pacjenci (nazwiskoimie,adres,skierowany,opis) values (#nazwiskoimie,#adres,#skierowany,#opis)";
cmd.Parameters.AddWithValue("#nazwiskoimie", txtnazwiskoimie.Text);
cmd.Parameters.AddWithValue("#adres", txtadres.Text);
cmd.Parameters.AddWithValue("#skierowany", txtskierowany.Text);
cmd.Parameters.AddWithValue("#opis", txtopis.Text);
cmd.ExecuteNonQuery();
conn.Close();
Can someone tell me what I'm doing wrong?
I've tried tons of samples about insert data, but it doesn't work.
I can manage .MDF, but .SDF seems quite problematic.
Hope you help me

Ok, I'm going to take a guess here. Is the PacjenciDB.sdf included into Visual Studio project by any chance? Do you have the property "Copy to output folder" set to "Always" or something similar? It seems that every time you do a build you could be overwriting your output folder database file. Try putting the database in a folder that is not inside VS project.
BTW, your code is OK.

Look for a copy of the database with data in your bin/debug folder.
Solution is to not use |DataDirectory|, but use full path instead.

The above code is correct and most likely the problem is somewhere else, where you call that code from. If there is a problem with db connection or data is wrong - you should get an exception. Since there is no error occurred and no new records added - the code is not executed at all.
P.S.
.sdf is a Sql Server Compact Local Database, so using System.Data.SqlServerCe is correct
http://msdn.microsoft.com/en-us/library/system.data.sqlserverce(v=vs.100).aspx

Try using double backslash when setting the path to your database file:
string dbPath + "Data Source=C:\\DataDirectory\\PacjenciDB.sdf";
SqlCeConnection conn = new SqlCeConnection(dbPath);
conn.Open();
SqlCeCommand cmd = conn.CreateCommand();
cmd.CommandText="INSERT INTO pacjenci (nazwiskoimie,adres,skierowany,opis) values (#nazwiskoimie,#adres,#skierowany,#opis)";
cmd.Parameters.AddWithValue("#nazwiskoimie", txtnazwiskoimie.Text);
cmd.Parameters.AddWithValue("#adres", txtadres.Text);
cmd.Parameters.AddWithValue("#skierowany", txtskierowany.Text);
cmd.Parameters.AddWithValue("#opis", txtopis.Text);
cmd.ExecuteNonQuery();
conn.Close();

Using a View from SQL Server 2008 in C# & Asp.net

I have a C#/ASP.net project has included a database that I have developed that includes a nice and convenient View that would be handy to use.
I have the SQL connection setup to a SQL Server 2008 DB I created. It seems as though it is connecting fine, but I don't understand how to actually use the View that I created without hard coding the query into the program (been told this is bad sometimes?).
This is my connection I setup:
SqlConnection conn = null;
conn = new SqlConnection("Data Source=raven\\sqlexpress;Initial Catalog=ucs;Integrated Security=True;Pooling=False");
conn.Open();
SqlCommand command = new SqlCommand(query, conn);
Basically, I need some code to query using this View. I can see the View and look at the results that would be obtained, but not access it in the program!
The view is named "UserView". Help is much appreciated!

You could use something like the following. But it's usually considered evil to put hardcoded SQL commands into .Net code. It's much better and safer to use stored procedures instead.
This should get you started. You can modify it to use stored procedures by
changing the command.CommandType to indicate it's a stored proc call
And adding the proper parameters to the command that your SP needs.
Change command.CommandText to the name of your SP, thus
eliminating the hardcoded SQL.
sample code below:
using (SqlConnection connection = new SqlConnection("Data Source=raven\\sqlexpress;Initial Catalog=ucs;Integrated Security=True;Pooling=False"))
{
using (SqlCommand command = connection.CreateCommand())
{
command.CommandText = "SELECT * from your_view WHERE your_where_clause";
connection.Open();
using (SqlDataReader reader = command.ExecuteReader())
{
while (reader.Read())
{
// process result
reader.GetInt32(0); // get first column from view, assume it's a 32-bit int
reader.GetString(1); // get second column from view, assume it's a string
// etc.
}
}
}
}

Using VS2013 add a new DataSet to your project. Drag your View from the Server Explorer to the DataSet Design Surface.

How do I access a database in C#

Basically, I would like a brief explanation of how I can access a SQL database in C# code. I gather that a connection and a command is required, but what's going on? I guess what I'm asking is for someone to de-mystify the process a bit. Thanks.
For clarity, in my case I'm doing web apps, e-commerce stuff. It's all ASP.NET, C#, and SQL databases.
I'm going to go ahead and close this thread. It's a little to general and I am going to post some more pointed and tutorial-esque questions and answers on the subject.

MSDN has a pretty good writeup here:
http://msdn.microsoft.com/en-us/library/s7ee2dwt(VS.71).aspx
You should take a look at the data-reader for simple select-statements. Sample from the MSDN page:
private static void ReadOrderData(string connectionString)
{
string queryString =
"SELECT OrderID, CustomerID FROM dbo.Orders;";
using (SqlConnection connection = new SqlConnection(
connectionString))
{
SqlCommand command = new SqlCommand(
queryString, connection);
connection.Open();
SqlDataReader reader = command.ExecuteReader();
try
{
while (reader.Read())
{
Console.WriteLine(String.Format("{0}, {1}",
reader[0], reader[1]));
}
}
finally
{
// Always call Close when done reading.
reader.Close();
}
}
}
It basicly first creates a SqlConnection object and then creates the SqlCommand-object that holds the actual select you are going to do, and a reference to the connection we just created. Then it opens the connection and on the next line, executes your statements and returns a SqlDataReader object.
In the while-loop it then outputs the values from the first row in the reader. Every time "reader.Read()" is called the reader will contain a new row.
Then the reader is then closed, and because we are exiting the "using"-secret, the connection is also closed.
EDIT: If you are looking for info on selecting/updating data in ASP.NET, 4GuysFromRolla has a very nice Multipart Series on ASP.NET 2.0's Data Source Controls
EDIT2: As others have pointed out, if you are using a newer version of .NET i would recommend looking into LINQ. An introduction, samples and writeup can be found on this MSDN page.

The old ADO.Net (sqlConnection, etc.) is a dinosaur with the advent of LINQ. LINQ requires .Net 3.5, but is backwards compatible with all .Net 2.0+ and Visual Studio 2005, etc.
To start with linq is ridiculously easy.
Add a new item to your project, a linq-to-sql file, this will be placed in your App_Code folder (for this example, we'll call it example.dbml)
from your server explorer, drag a table from your database into the dbml (the table will be named items in this example)
save the dbml file
You now have built a few classes. You built the exampleDataContext class, which is your linq initializer, and you built the item class which is a class for objects in the items table. This is all done automatically and you don't need to worry about it. Now say I want to get record with the itemID of 3, this is all I need to do:
exampleDataContext db = new exampleDataContext(); // initializes your linq-to-sql
item item_I_want = (from i in db.items where i.itemID == 3 select i).First(); // using the 'item' class your dbml made
And that's all it takes. Now you have a new item named item_I_want... now, if you want some information from the item you just call it like this:
int intID = item_I_want.itemID;
string itemName = item_I_want.name;
Linq is very simple to use! And this is just the tip of the iceberg.
No need to learn antiquated ADO when you have a more powerful, easier tool at your disposal :)

Reads like a beginner question. That calls for beginner video demos.
http://www.asp.net/learn/data-videos/
They are ASP.NET focused, but pay attention to the database aspects.

topics to look at:
ADO.NET basics
LINQ to SQL
Managed database providers

If it is a web application here are some good resources for getting started with data access in .NET:
http://weblogs.asp.net/scottgu/archive/2007/04/14/working-with-data-in-asp-net-2-0.aspx

To connect/perform operations on an SQL server db:
using System.Data;
using System.Data.SqlClient;
string connString = "Data Source=...";
SqlConnection conn = new SqlConnection(connString); // you can also use ConnectionStringBuilder
connection.Open();
string sql = "..."; // your SQL query
SqlCommand command = new SqlCommand(sql, conn);
// if you're interested in reading from a database use one of the following methods
// method 1
SqlDataReader reader = command.ExecuteReader();
while (reader.Read()) {
object someValue = reader.GetValue(0); // GetValue takes one parameter -- the column index
}
// make sure you close the reader when you're done
reader.Close();
// method 2
DataTable table;
SqlDataAdapter adapter = new SqlDataAdapter(command);
adapter.Fill(table);
// then work with the table as you would normally
// when you're done
connection.Close();
Most other database servers like MySQL and PostgreSQL have similar interfaces for connection and manipulation.

If what you are looking for is an easy to follow tutorial, then you should head over to the www.ASP.net website.
Here is a link to the starter video page: http://www.asp.net/learn/videos/video-49.aspx
Here is the video if you want to download it: video download
and here is a link to the C# project from the video: download project
Good luck.

I would also recommend using DataSets. They are really easy to use, just few mouse clicks, without writing any code and good enough for small apps.

If you have Visual Studio 2008 I would recommend skipping ADO.NET and leaping right in to LINQ to SQL

#J D OConal is basically right, but you need to make sure that you dispose of your connections:
string connString = "Data Source=...";
string sql = "..."; // your SQL query
//this using block
using( SqlConnection conn = new SqlConnection(connString) )
using( SqlCommand command = new SqlCommand(sql, conn) )
{
connection.Open();
// if you're interested in reading from a database use one of the following methods
// method 1
SqlDataReader reader = command.ExecuteReader();
while (reader.Read()) {
object someValue = reader.GetValue(0); // GetValue takes one parameter -- the column index
}
// make sure you close the reader when you're done
reader.Close();
// method 2
DataTable table;
SqlDataAdapter adapter = new SqlDataAdapter(command);
adapter.Fill(table);
// then work with the table as you would normally
// when you're done
connection.Close();
}