Develop Reference

Querying 2 datatables in a dataset

I have 2 datatables named 'dst' and 'dst2'. they are located in the dataset 'urenmat'.
The mayority of the data is in 'dst'. this however contains a column named 'werknemer'. It contains a value which corresponds to a certain row in 'dst2'. This column is named 'nummer'.
What i need is a way to left outer join both datatables where dst.werknemer and dst2.nummer are linked, and a new datatable is created which contains 'dst2.naam' linked to 'dst.werknemer' along with all the other columns from 'dst'.
I have looked everywhere and still can't seem te find the right answer to my question. several sites provide a way using LINQ in this situation. I have tried using LINQ but i am not so skilled at this.
I tried using the 101 LINQ Samples:
http://code.msdn.microsoft.com/101-LINQ-Samples-3fb9811b
urenmat = dataset.
dst = a, b, c, d, werknemer.
dst2 = nummer, naam.
I used the following code from '101'.
var query =
from contact in dst.AsEnumerable()
join order in dst2.AsEnumerable()
on contact.Field<string>("werknemer") equals
order.Field<string>("nummer")
select new
{
a = order.Field<string>("a"),
b = order.Field<string>("b"),
c = order.Field<string>("c"),
d = order.Field<string>("d"),
naam = contact.Field<decimal>("naam")};
I however don't know what to change 'contact' and 'order' to and i can't seem to find out how to save it to a datatable again.
I am very sorry if these are stupid questions but i have tried to solve it myself but it appears i'm stupid:P. Thank for the help in advance!
PS. i am using C# to code, the dataset and datatables are typed.

if you want to produce a projected dataset of dst left outer joined to dst2 you can use this LINQ expression (sorry i don't really work in LINQ query syntax so you'll have to use this lambda syntax instead).
var query = dst.AsEnumerable()
.GroupJoin(dst2.AsEnumerable(), x => x.Field<string>("werknemer"), x => x.Field<string>("nummer"), (contact, orders) => new { contact, orders })
.SelectMany(x => x.orders.DefaultIfEmpty(), (x, order) => new
{
a = order.Field<string>("a"),
b = order.Field<string>("b"),
c = order.Field<string>("c"),
d = order.Field<string>("d"),
naam = x.contact.Field<decimal>("naam")
});
because this is a projected dataset you cannot simply save back to the datatable. If saving is desired then you would want to load the affected row, update the desired fields, then save the changes.
// untyped
var row = dst.Rows.Find(keyValue);
// typed
var row = dst.FindBy...(keyValue);
// update the field
row.SetField("a", "some value");
// save only this row's changes
row.AcceptChanges();
// or after all changes to the table have been made, save the table
dst.AcceptChanges();
Normally if you need to perform loading and saving of (projected) data, an ORM (like entity framework, or LINQ-to-SQL) would be the best tool. However, you are using DataTable's in this case and I'm not sure if you can link an ORM to these (though it seems like it would probably be possible).

How to join tables using include with entity SQL

I will try to describe my issue in details.I have the following scenario.
1.) I have 3 tables : business, customoffice(Custom Office) and cusdesc(custom office description)
The relationship is that a business has on customoffice and one customoffice has many cusdesc.
The table business has a field customofficeno which is a foreign key to the field cuscode of the customoffice table.The table cusdesc has a field cuscode which is a foreign key to the field cuscode of the customoffice table.
The objective is to select a business including the custom office and custom office description using entity framework.
2.) Code
I have a procedure FillData which fills a datagrid. My objective is to display fields from the 3 tables. I managed to display data from tables "Business" and "Customoffice" but i need to display the description of a custom office via table "cusdesc" and be more specific the field "CSNAME".
3.) My issue is that when I include the ("CUSTOMSOFFICE.CUSDESC") the results do not contain data from table "CUSDESC" but only how many records much the criteria so I cannot access the field "CSNAME"
Hereafter is the procedure:
using (var _context = new ReftabEntities())
{
try
{
SetGlobalValues();
ObjectQuery<BUSINESS> q_business = _context.BUSINESS.Where("it.BUSINESSNO=" + int.Parse(pv_businessno)).Where(string.Format("(it.BUSINESSSTART <= DATETIME'{0:yyyy-MM-dd HH:mm}') and (it.BUSINESSCLOSED >= DATETIME'{0:yyyy-MM-dd HH:mm}')", pv_date)).Include("CUSTOMSOFFICE").Include("CUSTOMSOFFICE.CUSDESC");
gvBusinessList.Caption = "Total records selected: " + q_business.Count();
gvBusinessList.DataSource = q_business;
gvBusinessList.DataBind();
}
catch (Exception e)
{
errorPopup.Text = e.Message;
errorPopup.ShowOnPageLoad = true;
}
finally
{
_context.Dispose();
}
}
}
Can you please give a hint what I do wrong.
Thanks in advance.

The Include operator just asks EF to load a related entity with the query. If you don't use "Include", EF will only extract the properties of BUSINESS and will not extract the properties of the CUSTOMSOFFICE. There is no need for the "Include("CONSOMSOFFICE.CUSDESC")" since you already loaded the entire CUSTOMSOFFICE entity in the first Include.
I see that you're binding the result to the grid view, and if I understand correctly, the issue is that the "CUSTOMSOFFICE.CUSDESC" is not being displayed in the gridview. I believe this is because the gridview tries to render its representation of the "CUSTOMSOFFICE" object itself, since that's the direct property of the items you are binding. To have more control over the "columns" of your gridview, I suggest using LINQ to transform the results of your query into what you explicitly want to display.
I am assuming that BUSINESSNO, BUSINESSSTART, and BUSINESSCLOSED are properties of your Business entity itself, and that BUSINESSNO is the Primary Key. Let me rewrite your query into this:
var q_business = _context.BUSINESS.Include(b=>b.CUSTOMSOFFICE)
.Where(p => p.BUSINESSNO == int.Parse(pv_businessno)
&& p.BUSINESSSTART <= DateTime.Parse(pv_date)
&& p.BUSINESSCLOSED >= DateTime.Parse(pv_date) )
.FirstOrDefault();
This query would extract the details of the Business (including the related CUSTOMSOFFICE details) that matches the given pv_businessno and falls within your date criteria. But you can't bind this to your gridview yet because you might encounter the same problem where the CUSTOMSOFFICE.DESC is not displayed. To ensure proper display, you must identify what properties you want to include. For example, if you only want to display the set of properties below:
BUSINESS.BUSINESSNO
BUSINESS.BUSINESSNAME
BUSINESS.CUSTOMSOFFICE.CUSCODE
BUSINESS.CUSTOMSOFFICE.CUSDESC
You should transform your output to explicitly and immediately include these properties.
var q_business = _context.BUSINESS.Include(b=>b.CUSTOMSOFFICE)
.Where(b => b.BUSINESSNO == int.Parse(pv_businessno)
&& b.BUSINESSSTART <= DateTime.Parse(pv_date)
&& b.BUSINESSCLOSED >= DateTime.Parse(pv_date) )
.Select(b => new {BusinessNo = b.BUSINESSNO,
BusinessName = b.BUSINESSNAME,
CustomsOfficeCode = b.CUSTOMSOFFICE.CUSCODE,
CustomsOfficeDesc = b.CUSTOMSOFFICE.CUSDESC } ) //This Select statement creates a new anonymous type that has Businessno, BusinessName, CustomsOfficeCode, and CustomsOfficeDesc properties
.FirstOrDefault();
When you bind this to your gridview, it should be able to display the value of the CUSDESC property.

deleting list of records with linq-to-sql

I'm writing a linq-to-sql query to delete a list of records: I pass in a list of RecordID and I want the corresponding records deleted.
This is what I have so far:
public void DeleteMyRecords(List<long> TheRecordIDs)
{
using (TheDC MyDC = new TheDC()) //TheDC is the DataContext
{
MyDC.DeleteOnSubmit(from a in MyDC.TheTable
where TheRecordIDs.Contains(a.RecordID)
select a).SubmitChanges();
}
}
For now, I see the DeleteOnSubmit underlined in red. How do you write such query so that it works?
Thanks for your help.

As query may return more then one record you may need to call DeleteAllOnSubmit
var records = from a in MyDC.TheTable
where TheRecordIDs.Contains(a.RecordID)
select a;
MyDC.TheTables.DeleteAllOnSubmit(records);
MyDc.SubmitChanges();

Linq to Sql General Help - Insert Statement

I am currently trying to create a new order (which will be shown below) in a web service, and then send that data to insert a new row into the database. For some reason my DBML / Data Context does not allow me to use InsertOnSubmit.
Any ideas? I haven't used Linq to Sql in about 7 months.
Thanks in advance.
[WebMethod]
public string InsertOrderToDatabases()
{
//Start Data Contexts ------
DataContext db = new DataContext(System.Configuration.ConfigurationManager.AppSettings["RainbowCMSConnectionString"]);
DataContext dcSqlOES = new DataContext(System.Configuration.ConfigurationManager.AppSettings["OESConnectionString"]);
//Get table from local database
Table<Schedule> Schedule = db.GetTable<Schedule>();
//Find last order number in databases
var lastOrderNumber = from lOrder in Schedule
orderby lOrder.templ_idn descending
select lOrder.templ_idn;
int firstOrderID;
var firstOrder = lastOrderNumber.FirstOrDefault();
firstOrderID = firstOrder.Value + 1;
qrOrder qrOrd = new qrOrder
{
.... data in here creating a new order
};
//TODO: fix below with an insert on submit
if (qrOrd != null)
{
// **Schedule.InsertOnSubmit(qrOrd);**
}
//db.GetTable<Schedule>().InsertOnSubmit(qrOrd);
try
{
//Submit the changes to the database
db.SubmitChanges();
return "Orders were sent to the databases.";
}
catch ()
{
}
}

Based on your response, it appears that you are using the wrong table, or perhaps the wrong data type. I also noticed that when you declare your localSchedule variable, you declare it as type Table<Schedule>, which means it should contain Schedule entities, not qrOrder entities.
Table<TEntity>.InsertOnSubmit expects a specific strongly typed entity to be passed in. In your case, it is expecting Web_Service.Schedul‌e, but you are trying to pass in a qrOrder.

Schedule.InsertOnSubmit(qrOrd);
That line will not treat to submit changes to connected entity , Try this
db.Schedule.InsertOnSubmit(qrOrd);
db.SubmitChanges();

you can try with
db.GetTable(typeof(Schedule)).InsertOnSubmit(qrOrd);
Or
db.GetTable(qrOrd.GetType()).InsertOnSubmit(qrOrd);

Unable to search a SQL database under ASP.NET

I've added a LINQ-SQL link in my website to make objects and after that, I'm trying to write the neccesary code to search into a database.
In my case I am trying to display a column value assigned to another of other column into a DATABASE using the following code but I can't:
Palabras_Definiciones quintanaserena = new Palabras_Definiciones(); // LINQ
if (searchInput.Attributes["value"] == quintanaserena.palabra)
{
Label1.Text = quintanaserena.definición;
}
Am I doing anything wrong?

In the code above, you are not doing any request to the database. You only created the object that has the same definition as your database table.
To query your database, you need to do a query over your DataContext (usually the name of your .dbml file).
MSDN has a good web page to show sample of query. You might want to take a look there: http://code.msdn.microsoft.com/101-LINQ-Samples-3fb9811b
Your query would probably look like:
palabrasDataContext dcPalabras = new palabrasDataContext(); //palabrasDataContext would be the name of the DataContext you generated
Palabras_Definiciones quintanaserena = (from palabras in palabrasDataContext
where palabras.palabra == searchInput.Attributes["value"] //palabra is the name of the column
select palabras).FirstOrDefault(); //Using firstorDefault here if you have only one definition per word
if(quintanaserena != null) //FirstorDefault returns null if the resultset was empty
{
label1.Text = quintanaserena.definición;
}