So this is probably the most naive question but that is what questions are for I guess;
Then, my issue is that I have no idea on how to connect Visual C# Express 2010 to Access 2007 and do the typical insert, update, delete, search in an application in C#, I have just learned the basics (finished a console tutorial, which I believe is more than enought, having previous background of VB6 using access 97), and I have been searching here and in the web, but the only thing I could find where the msdn tutorials which I dind't find really clear.
So in my app I just need to link comboboxes, query those values to obtain new ones, do calculations and then store in arrays (and maybe show these in datagrids as well as edit them from said datagrids, which is a bit more complicated I guess) and finally store them in various tables, but I haven't really found a strong (or most likely simple) manual that will guide me to create the typical app insert, update, delete using winforms.
Do you guys have any good links in order to do this?
Thanks.
You can try with this code
Here link about string connection : http://www.connectionstrings.com/access-2007
var query = "...";
var connectionString = "...";
using (OleDbConnection connection = new OleDbConnection(connectionString))
{
// The insertSQL string contains a SQL statement that
// inserts a new row in the source table.
using(var command = new OleDbCommand(query))
{
// Set the Connection to the new OleDbConnection.
command.Connection = connection;
// Open the connection and execute the insert command.
try
{
connection.Open();
command.ExecuteNonQuery();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
// The connection is automatically closed when the
// code exits the using block.
}
}
Related
Before I start, I'll let you know that I tried everything that has already been suggested on previous questions and other websites before I considered posting a question myself. As it happens, nothing seems to work and I'm just about fed up with this.
As some background information, this is for my Computing A2 project, so I'm kind of stuck for time now - i.e. I can't be changing loads of my code ideally.
Anyway, onto the issue...
I'm using SQLCe in my code to read from various tables and write to one. So far, the code for reading from the tables works fine, so that's any connection issues out the way first. The piece of code I am struggling with is as follows:
string connectionString = Properties.Settings.Default.BookingSystemDatabaseConnectionString;
using (SqlCeConnection myConnection = new SqlCeConnection(connectionString))
{
myConnection.Open();
try
{
string commandStr = "INSERT INTO bookings(username, room, time) VALUES(#username, #room, #time)";
SqlCeCommand myCommand = new SqlCeCommand(commandStr);
//Passes parameters into SQL command.
myCommand.Parameters.AddWithValue("username", StaticUser.StudentUser.username);
myCommand.Parameters.AddWithValue("room", roomBox.Text);
myCommand.Parameters.AddWithValue("time", timeBox.Text);
//Executes SQL command. Returns the number of affected rows (unecessary for my purposes; a bi-product if you will).
myCommand.ExecuteNonQuery();
}
catch
{
System.Windows.Forms.MessageBox.Show("Could not write new booking to database. This is likely because the database cannot be reached.", "Error");
Program.AccessError = true;
}
myConnection.Close();
}
This is just one of the many ways I have tried to combat the issue I am having. I have also explored:
myCommand.Parameters.Add(new SqlCeParameter("username", StaticUser.StudentUser.username));
to pass the parameters...and another method which escapes me now (using ".Value = StaticUser.StudentUser.username" I think). Furthermore, I have tried using a 'using' statement for the command to save me closing the connection myself (I will probably end up using a solution that uses 'using'). Finally (albeit this isn't a chronological recollection), I tried:
SqlCeCommand myCommand = new SqlCeCommand("INSERT INTO bookings(username, room, time) VALUES(#username, #room, #time)", myConnection)
Again, of course, to no avail.
To highlight the actual symptoms of the issue I am having: The code appears to run fine; stepping through the full method I have pasted above shows that no error is being caught (of course, the message box does not appear - I realised afterwards that stepping through was arguably an unnecessary procedure) and in the other methods I have touched on, the same thing happens. The issue, then, is that the table 'bookings' is not actually being updated.
So, my question, why?
I didn't do the obvious and check the Debug folder for an updated database.
Look for a copy of the database file in your bin/debug folder.
Use full path in connection string, and preferably do not include the sdf file in your project (or at least set build action to None)
i think you are not defining a connection for the command
try
mycommand.connection = connectiostring;
Right, I have been tasked with developing a new application in MVC3 that unfortunately has to integrate very slightly with a classic asp web site. This won't be forever as the old site will get an update at some point, but not yet. In the mean time however the new MVC3 application will need a little bit of access to the database for the old site, which is a old MS Access .mdb whereas the new app will be using sql server 2008.
I would greatly appreciate it if someone could give me some examples of how to connect to the access db, aswell as how to execute sql queries (i am fine writing the sql, just got no idea how to execute against the database from my mvc3 app).
thanks in advance
EDIT: I've not got much experience with the old site, but it appears to use the JET adaptor if that helps! ;-)
Your question requires an answer too extensive to be given in detail
I will give you a check list of things and class to research
Define the connection string used to reach your database [see
here]
Create and open the OleDbConnection
Define your OleDbCommand and the command text to be executed
Create and use an OleDbDataReader to read your data line by line
Create and use an OleDbDataAdapter to read your data and load a
DataSet or DataTable
Now don't forget to close your connection and use parametrized query
string connectionString = Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\mydatabase.mdb;Jet OLEDB:Database Password=MyDbPassword;
public void InsertRow(string connectionString, string insertSQL)
{
using (OleDbConnection connection = new OleDbConnection(connectionString))
{
// The insertSQL string contains a SQL statement that
// inserts a new row in the source table.
OleDbCommand command = new OleDbCommand(insertSQL);
// Set the Connection to the new OleDbConnection.
command.Connection = connection;
// Open the connection and execute the insert command.
try
{
connection.Open();
command.ExecuteNonQuery();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
// The connection is automatically closed when the
// code exits the using block.
}
}
I have a problem,
private void button_Submit_Click(object sender, EventArgs e)
{
try
{
string connectionString = #"Data Source=Database_TouchPOS.sdf;Persist Security Info=False;";
using (SqlCeConnection connection = new SqlCeConnection(connectionString))
{
using (SqlCeCommand command = connection.CreateCommand())
{
connection.Open();
command.CommandText = "INSERT INTO Product (Title,Price,Category_Id) VALUES (#title, #price,#category_Id)";
command.Parameters.AddWithValue("#title", textBox_Title.Text);
command.Parameters.AddWithValue("#price", textBox_Price.Text);
command.Parameters.AddWithValue("#category_Id", comboBox_Category.SelectedIndex);
command.ExecuteNonQuery();
MessageBox.Show("Product Added Successfully...");
}
connection.Close();
}
}
catch (SqlException ex)
{
MessageBox.Show(ex.Message);
}
}
Everything seem to be fine, but still can't add data into database.
I did try with complete database path, example c:\project\database.sdf
I did a lot of search before asking. I saw similar problems but not even a single one works for me.
Data are added when compiling but not committed to database. I can see the data after second attempt of debugging.
Please kindly try to explain in detail.
Thanks
You are probably facing this, http://erikej.blogspot.com/2010/05/faq-why-does-my-changes-not-get-saved.html suggest you use a full path to your database file in your connection string.
Did you try to use transactions explicitly?
IDbTransaction transaction = connection.BeginTransaction();
//add to database
transaction.Commit(); // before close connection
This is a very old thread, so I don't know if it will help anyone if I put my answer.
I had this problem, too.
When I executed an update or insert code in C#, apparently, everything was ok, but when I looked up the database, there was no change.
The thing was that while debugging I had the database opened in a Management Studio. And somehow this obstructed the database changes even when there was no error message.
Closing the Management Studio and opening it after executing the code, the changes where perfectly stored in the data base.
Regards.
complete example for those seeking like me... #"Data Source=C:\Users\MYPC\Documents\Visual Studio 2010\Projects\MyProjectFolder\MyProject-1\bin\Debug\MyDatabase.sdf;Persist Security Info=False;";
thank for this example. This saved my day.
i wanna to attach a Database from a dynamic path to a MSSQL server by coding a project to do this ,,
what is the code i should write and will it be a Windows Application or Console Application ,, or there is no difference ??
You can use any of the two. Just make sure the files are in a place the SQL Server in question can reach and then attach them with an sql statement.
Like this:
CREATE DATABASE [AdventureWorks] ON
( FILENAME = N’C:\Data\AdventureWorks_Data.mdf’ ),
( FILENAME = N’C:\Data\AdventureWorks_Log.ldf’ )
FOR ATTACH
In the connection string you can attach a database if the database has not already been attached. To do this in C# you should be able to do the following (this is untested):
SQLConnection conn;
try
{
conn = new SQLConnection(String.Format("Server={0};AttachDbFilename={1};Database=dbname; Trusted_Connection=Yes;", "Server Address", #"Path To Database"));
conn.Open();
conn.Close();
}
catch (Exception ex)
{
throw;
}
finally
{
conn.Dispose();
}
Let me know how you get on.
Regards,
Stu
Are you talking about using System.Data.SqlConnection class?
You can dynamically build your connectionString when you create your SqlConnection.
If I nderstand your question correctly, you are looking for a way to use a databse which the user will select (not the hard coded one).
Go here and learn about Saving User and Application Settings in WinForms. You will get some ideas.
I'm trying to build a program that uses a C# to work with a MySQL DB. I get the C# syntax, and can write the language, but I don't have much experience with the libraries, and I feel a bit lost.
Could someone post examples of how a program would be built (in technical terms, syntax would be nice, but pseudo code is fine, too)?
I understand the theory of how it works, but need a hands on approach to it.
Thank you.
EDIT
I forgot to add that I want to learn how to do it with the .NET v.2.0 framework / VS2005 / MySQL v5.0 combination.
EDIT # 2
2.0 .NET will only be supported. =)
Here is tutorial for Entity Framework + MySQL.
There are lots of other ways to operate with DB, depending on what you need:
If you need execute raw sql queries against DB - use OdbcConnection + OdbcCommand
Need to manipulate items in DB as objects - use ORM (EntityFramework, NHibernate, Linq2Sql)
Like old-style DB interop? - DataSets is your choice.
I really like EF. Easy thing to start with.
PS: And before mixing UI and DB-interop, please read about Separation of concerns. MVC is interesting to read about too. About "libraries": create another project in your solution and add DB-interop logics there. Don't mix it in one assembly, because when your project becomes bigger than "Hello DataBase!" application it will create a big mess in code and logics, really.
UPDATE:
Using VS2005 and .net 2.0 is mysterious idea, really. Lots of tools and assemblies where made since 2.0 release. Linq, Orm-s, etc. Live without them is hard and all the benefits of C# are lost. I highly recommend to use latest techniques, if there is no strict reasons to use 2.0.
If using SqlServer - ObdcCommand and OdbcConnection can be replaced to SqlCommand and SqlConnection. (thanks #Abe Miessler comment)
Here is an example swiped from MSDN:
public void InsertRow(string connectionString, string insertSQL)
{
using (OdbcConnection connection =
new OdbcConnection(connectionString))
{
// The insertSQL string contains a SQL statement that
// inserts a new row in the source table.
OdbcCommand command = new OdbcCommand(insertSQL, connection);
// Open the connection and execute the insert command.
try
{
connection.Open();
command.ExecuteNonQuery();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
// The connection is automatically closed when the
// code exits the using block.
}
}
If you want to read records in a DB, look at this example:
public static void ReadData(string connectionString)
{
string queryString = "SELECT DISTINCT CustomerID FROM Orders";
using (OdbcConnection connection = new OdbcConnection(connectionString))
{
OdbcCommand command = new OdbcCommand(queryString, connection);
connection.Open();
// Execute the DataReader and access the data.
OdbcDataReader reader = command.ExecuteReader();
while (reader.Read())
{
Console.WriteLine("CustomerID={0}", reader[0]);
}
// Call Close when done reading.
reader.Close();
}
}
FYI i am just copy/pasting these directly from MSDN. I highly recommend reading over their documentation and looking at their examples if you are just getting started.
http://msdn.microsoft.com/en-us/library/system.data.odbc.odbcdatareader.aspx
Here is a blog post getting you started with MySql and C#.
http://blog.bobcravens.com/2010/06/the-repository-pattern-with-linq-to-fluent-nhibernate-and-mysql/
Hope that gets you started.
Bob