Develop Reference

The Add method does not insert a new record into the database

The Add method does not insert a new record into the database.
Working with the database through the application.
The SelectAll request is executed.
The Insert request is not executed. There are no errors.
The Insert request code. Not running(Not working)
public void Insert(Source source)
{
using (var DbContext = new DbContextSQlite())
{
dbContext.Sources.Add(source);
dbContext.SaveChanges();
}
}
The selectAll request code.
Public void selectAll() is running
{
using (var DbContext = new DbContextSQlite())
{
var rows = from x in dbContext.Sources
select x;
int count = rows.Count();
}
}
Working with the database via DB Browser using SQL queries
The Select query is executed.
The Insert request is being executed.
Used.
DB Browser for SQLite Version 3.12.2;
Visual Studio Community 2019. 16.11.10;
Application-Console. .NET Framework 4.7.2;
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Update-1
Update-1.
When I try to fully post a question, stackoverflow.com gives me comments on the design. I don't understand how to eliminate these comments.
That's why I'm posting the question in an online editor.
Follow the link -> Detailed question.

How can I move data query away from user form. Winform C#

I'm completely new to C# programming and I'm trying to learn on my own. Currently I'm building a mini-project to exercise.
I understand that the user layer should not have any data query for security reasons perhaps?
So I have created a separate Data Access class to retrieve data. This is what my data access class looks like(I'll be using stored procedures for better security once I learn how to use it):
public class DataAccess
{
public List<Customer> FilteredCustomersList(string name)
{
using (IDbConnection connection = new MySql.Data.MySqlClient.MySqlConnection(Helper.CnnVal("FineCreteDB")))
{
var output = connection.Query<Customer>($"SELECT * from `Customers` WHERE `Cust_Name` LIKE '{name}'").ToList();
return output;
}
}
Basically I send over a string from the user form to query the database, the data is retrieved and stored in a list. User form:
private void RetrieveData()
{
try
{
DataAccess db = new DataAccess();
filteredcustomers = db.FilteredCustomersList(CustomerNameTxtBox_AutoComplete.Text);
ntn_num = filteredcustomers.Select(x => x.Cust_NTN).ElementAt(0);
strn_num = filteredcustomers.Select(x => x.Cust_STRN).ElementAt(0);
address = filteredcustomers.Select(x => x.Cust_Address).ElementAt(0);
phone_num = filteredcustomers.Select(x => x.Cust_Phone).ElementAt(0);
id_num = filteredcustomers.Select(x => x.Cust_ID).ElementAt(0);
}
catch (Exception)
{
MessageBox.Show("Customer not found. If customer was recently added, try updating DB.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
DataAccess db = new DataAccess();
filteredcustomers = db.AllCustomersList();
ntn_num = "";
strn_num = "";
address = "";
phone_num = "";
}
}
On the user form side, "filteredcustomers" holds the list of data sent back, now here is the problem: I use the filteredcustomers list to extract the different column values like so:
address = filteredcustomers.Select(x => x.Cust_Address).ElementAt(0);
and then use them to populate the respective textboxes like:
Address_TxtBox.Text = address;
Everything works fine, but I don't want the userform to have these queries for all individual columns, because from what I've understood so far, this is bad programming and bad for security as well.
Can anyone guide me how I can keep the values in Data Access layer and just call them into my form?
I'm sorry if this is a long post, I'm just learning and wanted to be as detailed as possible.

You're already doing everything reasonably correctly as per how Dapper is to be used. Dapper doesn't maintain a local graph of entities from the db, track changes to it and automatically save them. If you want that, use something like EF
For dapper you retrieve data with a SELECT and send it back with an UPDATE
If you're only expecting one Customer for the name, do this:
var output = connection.QueryFirstOrDefault<Customer>($"SELECT * from `Customers` WHERE `Cust_Name` LIKE #n", new { n = name });
https://dapper-tutorial.net/queryfirst
This will return just one customer instance (or null; check it!) meaning you can tidy up your form code to:
c = db.FilteredCustomer(CustomerNameTxtBox_AutoComplete.Text);
ntn_num = c?.Cust_NTN;
strn_num = c?.Cust_STRN;
And so on
Your "if customer was recently added try updating db" doesn't really make sense- the query is done live, so the db is about as up to date as it can be

LinqPad connect two azure databases on same server

Per the FAQ (1), I can add additional databases to my existing connection in a number of ways. I have tried them all, and none work for SQL Azure.
In fact, SQL Azure as a provider, doesn't even include the option to "Include additional databases."
Can someone please tell me a workaround for LinqPad to connect two databases? I am trying to create a migration linqpad script to sync data from one database to another.
http://www.linqpad.net/FAQ.aspx#cross-database

This fails because SQL Azure does not let you create linked servers. See
Can linked server providers be installed on a SQL Azure Database instance?
If you simply want to copy data from one database to another, and the schemas are the same, a workaround is to create a separate connection using the same TypedDataContext class:
void Main()
{
CopyFrom<Customer>("<source connection string>");
}
void CopyFrom<TTable> (string sourceCxString) where TTable : class
{
// Create another typed data context for the source. Note that it must have compatible schema:
using (var sourceContext = new TypedDataContext (sourceCxString) { ObjectTrackingEnabled = false })
{
// Delete the rows currently in our table:
ExecuteCommand ("delete " + Mapping.GetTable (typeof (TTable)).TableName);
// Insert the rows from the source table into the target table and submit changes:
GetTable<TTable>().InsertAllOnSubmit (sourceContext.GetTable<TTable>());
SubmitChanges();
}
}
Simple Select Example:
void Main()
{
SimpleSelect("<your conn string>");
}
void SimpleSelect (string sourceCxString)
{
// Create another typed data context for the source. Note that it must have compatible schema:
using (var sourceContext = new TypedDataContext (sourceCxString) { ObjectTrackingEnabled = false })
{
sourceContext.Assignee.OrderByDescending(a => a.CreateTimeStamp).Take(10).Dump();
Assignee.OrderByDescending(a => a.CreateTimeStamp).Take(10).Dump();
}
}

Unable to save data to Entity Model Database using saveChanges() method

I am trying to save data to my database. What I want is that when the button is pressed, data is saved to the database permanently. I've done tests where code is saved while the application is running. The saved data is viewable. But when I terminate the application, the data is not present when I view the data for that table in visual studio. I've provided the code that I am using for testing.
private void btn_otrFun_Click(object sender, EventArgs e)
{
tblCheese cheese = new tblCheese();
string cheesename = "TestCheese";
cheese.CheeseName = cheesename;
cheese.CheeseGroup = 1;
cheeseEntity.tblCheese.AddObject(cheese);
cheeseEntity.SaveChanges();
}
Here is where I am getting the context form. It is instantiated at the beginnning of the form.
private CheeseWorld_DatabaseEntities cheeseEntity = new CheeseWorld_DatabaseEntities(); //instanciate new database entities
And further I am using this snippet to retrieve data from the the database to dynamically created buttons.
var cheeselist = cheeseEntity.ExecuteStoreQuery<tblCheese>("Select * FROM tblCheese WHERE cheeseGroup = 1", null).ToList();
Hope these further details help. If more are required, let me know.

You've departed from the normal pattern we usually use for this... maybe try putting it back to something like this... (I don't see where you are getting the context)
using (var context = new cheeseEntity()) {
tblCheese cheese = new tblCheese();
cheese.CheeseName = "TestCheese";
cheese.CheeseGroup = 1;
context.tblCheese.Add(cheese);
context.SaveChanges();
}
This is covered in the documentation: http://msdn.microsoft.com/en-us/data/jj593489
(Pay attention to the bottom where it shows how to trace the generated SQL)
NOTE: I am using Add instead of AddObject.

Linq to Sql not submitting changes to database file in console app

I have an issue with my Linq to SQL Data Context no submitting in my console application.
The following code is all that there is in the main() method.
BlogRollerDataContext bdc = new BlogRollerDataContext();
bdc.Urls.InsertOnSubmit(new Url()
{
Approved = false,
UrlTo = "http://www.google.com/",
UrlFrom = ""
});
bdc.SubmitChanges();

This might help you.