I am using Microsoft LightSwitch framework, need to add dynamic items in choice list. So far I found different posts saying that choice list is only for static items and you have to use a separate table if you need to populate it in non-static means.
In my case, table will also not be a good option, I want to add items manually from C# code. Actually I need to populate years combobox, for this I need to add last 3 years, current year, and one next year. This I could not achieve through static data or TABLE will also be not a good idea.
just create a lookup table and add a relationship and LS will do the rest
You can always dynamically populate the new table
Although you won't be able to delete records that have children
Related
I want to create a dynamic 2-dimensional array (or any other structure) based on a dynamic database table in C# or T-SQL, which means the data source (which is a database table) is dynamic too.
EDIT:
Table structure:
For example:
If User1 meets the condition of Admin and Group1, it will be inserted into (Admin, Group1). And the users are constantly added in with different user type and group. So, every cellular can have as many as users.
And the problem is I don't know how many user types and groups there are, because new user types and new groups are added constantly too.
For now, I think I need to parse every data to find if it meets the existing conditions. If yes, insert it into the specific condition; if not, create a new condition and insert data into it.
But I don't have any idea about how to implement it? Do you have any ideas or algorithms?
Thanks very much for any suggestion or information.
I've solved this statically with Tuple, but not dynamically. I think I should re-fresh my tuple list periodically. But at least, it works now!
Any suggestions are welcome! Thanks!
I have an object whose fields I would like to store in a database. I will be using SQL Server Compact Edition (with Visual C# Express 2010). For the record, I'm fairly new to programming with databases (and databases in general). This program will be used every day to read emails, process the orders inside them, store them, and access them when necessary to help with completing the orders. The list of orders is going to become much to large to store in a List, write to a file, create the List from a file, etc. The problem is that each order contains a list of the items purchased. I am aware that I can serialize the list in binary or XML, and use that data as the field. However, this prevents me from searching/selecting based on that list. For instance, if I wanted to find an order based on what items are in it, or see how many times a particular item has been purchased. Since the list will be of arbitrary size, I can't just create a bunch of fields and fill only the ones I need (which in my opinion, is a bad idea anyway).
While writing this I realized a mistake. If I serialize the list again, I could compare the serialized data to find the same list again (though, this assumes that the same data is serialized the same way each time). However, I'm still prevented from finding any particular item.
So, is there any way to store the list of items, in a fixed number of fields (preferably 1) and still be able to search its contents with a query (I will most likely be using LINQ)?
Edit:
To address what I've gotten so far: first, thanks! I'm starting to piece together what I have to do, but I'm not quite there. The consensus seems to be to have a table for each set of items. Does that mean I'd be creating thousands of tables each month?
After re-reading my question I realize I have to be more clear. As the order comes in, I parse the data and store it in an Order object, which consists of the customer's information, and the list of items. Here is a simplified version of what I'm trying to store:
class Order{
private DateTime date;
private String orderNumber;
private String buyerName;
private List<Item> items;
private String address;
}
class Item{
private String itemCode;
private String description;
private int quantity;
}
So would I have to create a new table for each List I create, or am I missing something?
Update:
This may be a helpful reference for One-to-many relationships if you are new to the subject (especially check out the second and most upvoted answer): Create a one to many relationship using SQL Server
You'll want to create a new table in the database for your line items then create a foreign key relationship to the order table. It will be a one to many relationship. Some thing like the following - obviously you'll need to create a FK relationship, but you get the gist.
Existing
CREATE TABLE Order (
OrderID INT,
PONumber VARCHAR,
ItemsList VARCHAR
)
New
CREATE TABLE Order (
OrderID INT,
PONumber VARCHAR
)
CREATE TABLE LineItem(
LineItemID INT,
Description VARCHAR,
Quantity INT,
SequenceNumber INT,
OrderID INT -- <--- Important one here
)
Note that if you want to create just a simple lookup, the relationship would go the other way.
Instead of storing the list as a field, you can create a separate table that hold it's items. And records in this ListTable will have a field pointing to record ID in your original table. That way you can write various queries afterwards.
This can be solved in several ways, but if you want to be able to query the data directly, you should redesign your database with a seperate table where you store your list data with a reference ID. After all, databases are all about data lists.
I am developing a project which access a database in sql server 2012 through C# and performs CRUD modifications on it. Here is the main form:
both listboxes on the right are used to deal with informations contained in an intermediate tables (many-to-many relationship). Here is how they work: Basically, you choose types and abilities from the comboboxes, then click on 'add' and they are added in the respective listboxes. To delete items in the listboxes, you just need to select one item and then click 'delete'.
Here's another print to clear any doubts:
On the first print I've provided here, you will see a 'Bulbasaur' data. The PokémonID = 1 is represented by the 'Bulbasaur'; TypeID = 1 and 12 are 'Grass' and 'Poison', respectively; and AbilityID = 1 is 'Overgrow'.
I was trying to create an update function (update_click) using sql queries (SqlCommand, SqlDataReader and so on...), but without deleting the whole associations of a pokémon and its types (and abilities) and then re-adding them, based on the new modifications on the listboxes. I want to avoid it in order to save some memory in cases that some pokémon may hold thousands of types and abilities...
Is it possible? If necessary, I can send you my C# project for more details.
I would suggest a combination of:
1) Use table-valued parameters to send all the data (in its present state in your listboxes) to your T-SQL query or stored procedure at once
2) Consider using the EXCEPT and/or INTERSECT operators (as well as any necessary LEFT or RIGHT JOIN) to compare the contents of your table-valued parameter (essentially a table itself) with the data currently in the underlying tables
3) UPDATE/DELETE/INSERT accordingly
Essentially it sounds like what you are saying you'd like to do is to only "send the changes" to the database:
add any abilities that were not there before;
remove any abilities that were in the database but have been removed
If that's the case then what you need to be able to do is simple set operations:
Set Union
Set Intersect
Set Difference
while you can perform these operations using simple arrays or lists, it is much more efficient to use an actual set implementation such as a generic HashSet<>. With a correct implementation using sets or hash tables you ca achieve linear-time performance.
I hope this helps point you in the right direction..
I have developed an eCommerce application in C# and ASP.Net. For the Admin users "dashboard" landing page, I would like to give them a GridView that shows them the total sales dollar amount for a couple different time ranges, these would be my columns (ie last day, last week, last month, last year, total ever). I would like to give these values for orders that are in different status' (ie complete, paid but not shipped, in progress). Something similar to this:
|OrderStatus|Today|LastWeek|LastMonth|
|Processed |$10 |$100 |$34000 |
|PaidNotShip|$4 |$12 |$45 |
My question: What is the best/most efficient way to do this? I know that I could write separate SQL statements and union them together and bind the gridview to a sqldatasource:
(select amountForYesterday, amountForLastWeek from sales where orderStatus = processed)
UNION
(select amountForYesterday, amountForLastWeek from sales where orderStatus = paidnotshipped)
But that seems like a pain and very inefficient, since I would effectively be writing a separate query for each value.
I could also do this in the .cs page behind on load and programmatically populate the grid view row by row.
This GridView would only show information for the user's specific organization, so it would have to filter based on that as well.
I'm kind of at a loss as to how to do this without writing a massive query and continually hitting that query and database each time the page is viewed.
Any ideas?
I prefer using LINQ to work with data and/or GridViews (accessing the rows etc.). Have a look at a project I have on GitHub, which does exactly what I am mentioning here, as example. Note that this is just a sandbox I used previously for illustration purposes.
GitHub Repo
https://github.com/pauloosthuysen/int
Other useful info:
http://www.codeproject.com/Articles/33685/Simple-GridView-Binding-using-LINQ-to-SQL
The Sales etc. for LastWeek and LastMonth does not change very often. You could store that in a static Dictionary indexed by organization or summarize it in a separate table for faster access. This way you will not need to select the same huge amount of rows to get the same numbers over and over again. Unless special demands I would stick to the Dictionary solution because it is simple but a combination could also be a good solution
There is no direct way of doing it.
However instead of hitting the DB to the sum of every columns, you can perform the stuff using you datatable which is used for binging to your grid.
All you need to do is use
Dim iSumSal As Integer
iSumSal = StudentTable.Compute("SUM(sal)", "")
similarly you can perform for other columns.
once this is done. then just add a new row to you data table with all the summed values in it.
And then you can bind it to your grid.
optional - you can put some text value in the first column of you new row as "Total:"
thanks
rahul
Let's say we have a code list of all the countries including their country codes. The country code is primary key of the Countries table and it is used as a foreign key in many places in the database. In my application the countries are usually displayed as dropdowns on multiple forms.
Some of the countries, that used to exists in the past, don't exist any more, for example Serbia and Montenegro, which had the country code of SCG.
I have two objectives:
don't allow the user to use these old values (so these values should not be visible in dropdowns when inserting data)
the user should still be able to (readonly) open old stuff and in this case the deprecated values should be visible in dropdowns.
I see two options:
Rename deprecated values, for instance from 'CountryName' to '!!!!!CountryName'. This approach is the easiest to implement, but with obvious drawbacks.
Add IsActive column to Countries table and set it to false for all deprecated values and true for all other. On all the forms where the user can insert data, display only values which are active. On the readonly forms we can display all values (including deprecated ones) so the user will be able to display old data. But on some of my forms the user should be able to also edit data, which means that the deprecated values should be hidden from him. That means, that each dropbox should have some initialization logic like this: if the data displayed is readonly, then include deprecated values in dropbox and if the data is for edit also, then exclude them. But this is a lot of work and error prone too.
And other ideas?
I deal with this scenario a lot, and use the 'Active' flag to solve the problem, much as you described. When I populate a drop-down list with values, I only load 'active' data and include upto 1 deprecated value, but only if it is being used. (i.e. if I am looking at a person record, and that person has a deprecated country, then that country would be included in the Drop-downlist along with the active countries. I do this in read-only AND in edit modes, because in my cases, if a person record (for example) has a deprecated country listed, they can continue to use it, but once they change it to a non-deprecated country, and then save it, they can never switch back (your use case may vary).
So the key differences is, even in read-only mode I don't add all the deprecated countries to the DDL, just the deprecated country that applies to the record I am looking at, and even then, it is only if that record was already in use.
Here is an example of the logic I use when loading the drop down list:
protected void LoadSourceDropdownList(bool AddingNewRecord, int ExistingCode)
{
using (Entities db = new Entities())
{
if (AddingNewRecord) // when we are adding a new record, only show 'active' items in the drop-downlist.
ddlSource.DataSource = (from q in db.zLeadSources where (q.Active == true) select q);
else // for existing records, show all active items AND the current value.
ddlSource.DataSource = (from q in db.zLeadSources where ((q.Active == true) || (q.Code == ExistingCode)) select q);
ddlSource.DataValueField = "Code";
ddlSource.DataTextField = "Description";
ddlSource.DataBind();
ddlSource.Items.Insert(0, "--Select--");
ddlSource.Items[0].Value = "0";
}
}
If you are displaying the record as read-only, why bother loading the standing data at all?
Here's what I would do:
the record will contain the country code in any case, I would also propose returning the country description (which admittedly makes things less efficient), but when the user loads "old stuff", the business service recognises that this record will be read only, and you don't bother loading the country list (which would make things more efficient).
in my presentation service I will then generally do a check to see whether the list of countries is null. If not (r/w) load the data into the list box, if so (r/o) populate the list box from the data in the record - a single entry in the list equals read-only.
You can filter with CollectionViewSource or you could just create a Public Enumerable that filters the full list using LINQ.
CollectionViewSource Class
LINQ The FieldDef.DispSearch is the active condition. IEnumerable is a little better performance than List.
public IEnumerable<FieldDefApplied> FieldDefsAppliedSearch
{
get
{
return fieldDefsApplied.Where(df => df.FieldDef.DispSearch).OrderBy(df => df.FieldDef.DispName);
}
}
Why would you still want to display (for instance) customer-addresses with their OLD country-code?
If I understand correctly, you currently still have 'address'-records that still point to 'Serbia and Montenegro'. I think if you solve that problem, your current question would be none-existent.
The term "country" is perhaps a little misleading: not all the "countries" in ISO 3166 are actually independent. Rather, many of them are geographically separate territories that are legally portions or dependencies of other countries.
Also note that 'withdrawn country-codes' are reserved for 5 years, meaning that after 5 years they may be reused. So moving away from using the country-code itself as primary key would make sense to me, especially if for historical reasons you would need to back-track previous country-codes.
So why not make the 'withdrawn' field/table that points to the new country-id's. You can still check (in sql for instance, since you were already using a table) if this field is empty or not to get a true/false check if you need it.
The way I see it: "Country" codes may change, country's may merge and country's may divide.
If country's change or merge, you can update your address-records with a simple query.
If country's divide, you need a way to determine what address is part of what country.
You could use some automated system do do this (and write lengthly books about it).
OR
(when it is a forum like site), you could ask the users that still have a withdrawn country that points to multiple alternatives in their account to update their country-entry at login, where they can only choose from the list of new country's that are specified in the withdrawn field.
Think of this simplified country-table setup:
id cc cn withdrawn
1 DE Germany
2 CS Serbia and Montenegro 6,7
3 RH Southern Rhodesia 5
4 NL The Netherlands
5 ZW Zimbabwe
6 RS Serbia
7 ME Montenegro
In this example, address-records with country-id 3, get updated with a query to country-id 5, no user interaction (or other solution) needed.
But address-records that specify country-id 2 will be asked to select country-id 6 or 7 (of course in the text presented to the user you use the country-name) or are selected to perform your custom automated update routine on.
Also note: 'withdrawn' is a repeating group and as such you could/should make it into a separate table.
Implementing this idea (without downtime) in your scenario:
sql statement to build a new country-table with numerical id's as primary key.
sql statement to update address-records with new field 'country-id' and fill this field with the country-id from the new country-table that corresponds with country-code specified in that record's address-field.
(sql statement to) create the withdrawn table and populate the correct data with in it.
then rewrite your the sql statements that supply your forms with data
add the check and 'ask user to update country'-routine
let new forms go live
wait/see for unintended bugs
delete old country-table and (now unused) country-code column from the "address"-table
I am very curious what other experts think about this idea!!