Not sure how to word the question...
Basically, so far all my SQL stuff has been stored procedures and dumped into a gridview. The odd case where I had to perform an action based on a value (such as highlighting a row green if a certain value was true) were done as the gridview was rendering in one of the overrides.
Now however I have to do something far more complicated - pull three sets of data down, run a series of checks on all three and some date related checks and stuff, then populate a gridview with some of the items.
In logic terms, I want to run three queries, and store the lists of results (presumably in Lists?) then run some logic, then populate the gridview.
Specifically what I don't know how to do is:
Best way of pulling the data, and putting it into a List or other datastructure that lets me easily run through it, and retrieve data based on column (myList.age, or more likely, myList["Age"]).
One I have compared the data, I assume I create a new list that will be put into the gridview... how do I put the contents of a list INTO a gridview? How would I add other stuff such as buttons or checkboxes at the same time?
Any nudge in the right direction would be appreciated! Particularly doing cool stuff with lists and sql (if there is anything cool you can do with them)
There are actually several ways to do this with .Net without using an ORM solution. Instead trying to list all of them here I will link you to an article series that should help you accomplish what you want. The following series of articles is about N-Layer design, and includes answers to the information you are looking for. The first set of 4 articles were created some time ago with ASP.Net 2.0 then the author updated them with an additional six articles using ASP.Net 3.5
http://imar.spaanjaars.com/QuickDocId.aspx?quickdoc=476
If you want to avoid having to write SQL query and concentrate on the data instead, go with the Entity Framework. It's quite well integrated with VS. It will connect to your SQL database, you will tell it which tables to import, and it will create a series of classes for you to talk to your database.
Queries are quite easy to do, and they will return lists of objects which should be easy to manipulate and put to a grid later on.
You can create datatables and populate them using the lists that you have generated and then bind your grid using the newly created tables as the datasource.
Related
I have a DataGrid I'm binding to a DataTable, and displaying three BoundColumns as a result.
I would like to have a fourth column that connects with different data-- for instance, if column #3 in the DataGrid is a UserID, I would like to use that to query against a database and retrieve the user's first name, and display it in the fourth column.
Are there any recommended approaches to this? I'm not a DataGrid expert but should I be looking at a TemplateColumn or something along those lines?
Which event should I hook all this querying to, OnItemDataBound?
The recommended approach is return the user's first name as part of the original query and just use a BoundColumn. If you need to modify data before displaying, then yes you can use a TemplateColumn and the OnItemDataBound event to manipulate your data.
Running queries OnItemDataBound is not something I would ever encourage. So if your grid will show 100 records at once, you want to run 100 extra queries per page load? This is something that if you implement, could possibly run within reason during testing. Once under load though, you'll see have hundreds of extra queries running isn't a good idea... it can just be solved by fixing the original query or maybe making a denormalized table depending on your DB structure and the complexity of your query.
When I ran into similar issue, I went the denormalized table route.
Use a join in your sql statement to get the other value.
The project I am currently working requires retrieving/searching from large amount of data, the flow as below:-
Enter a keyword and search from about 500,000 members
Retrieve only top 6 members.
Allow sorting based on the member country or gender.
Requirements: Using EF5.0
The data is currently displayed using a UserControl and DataBinded using Repeater, will be updated through an UpdatePanel with next, previous button, etc.It is preferably but not limited to using EF5.0, and I am opened to other options (e.g. SqlDataReader) and cast it back to the members object manually.
My current solution calling the Entities with skip by using the page number, i.e.
members = context.Members.Where( conditions here ).Skip(page number * size).Take(size);
My question will be: Is my strategy the industrial / common ways of doing it? Anyone with similar experience can share with me in terms of performance / optimization, is there any other better way to do so?
I got really good performance using a stored procedure, instead of a LINQ query. This saves performance because of the query metadata generation/sql translation. If you are returning a large result set, disabling change tracking is a good option too.
I am using database paging which uses ROWCOUNT check it here https://web.archive.org/web/20211020131201/https://www.4guysfromrolla.com/webtech/042606-1.shtml and it gives really good performance with 200000 records including sorting and paging.
I'm working on a project in ASP.Net that uses the UpdatePanel to handle all AJAX requests. I'm much more familiar with using jQuery AJAX methods (and strategies) so I'm kind of stumped on finding a clean solution for the functionality I need.
Basically I need a table that allows me to dynamically add as many rows as I want using AJAX. These rows will contain text boxes whose values must be preserved by ASP.Net until I'm ready to submit the form. To further complicate matters there may already be records that exist in the database that should display as well with the values pre-populated and any changes to these fields must also be preserved.
I had started out by using a GridView and setting it's datasource to a list of the database records but unfortunately I believe this means I can't add new rows to the GridView.
Any assistance would be much appreciated. Keep in mind the solution must use ASP.Net controls.
I believe I figured out a solution that seems pretty straightforward.
When the page loads I gather any relevant records from the database and perform a query expression combined with a projection select to create an anonymous type array. When the add new row button is clicked instead of trying to add the row directly or retrieve potentially old data from the database I perform a query expression on the datagrid items themselves and union a new blank item. From there it's just a simple matter of setting the datagrid data source, triggering a databind and updating the update panel.
The only question now is how to identify the rows, particularly new rows that have no database keys yet. I could devise some clever method for generating row ids but I have a feeling that ASP.Net already does this and all I need to do is associate these ids with the anonymous types.
I have an ASP.NET data entry application that is used by multiple clients. The application consists of multiple data entry modules that are common to all clients.
I now have multiple clients that want their own custom module added which will typically consist of a dozen or so data points. Some values will be text, others numeric, some will be dropdown selections, etc.
I'm in need of suggestions for handling the data model for this. I have two thoughts on how to handle. First would be to create a new table for each new module for each client. This is pretty clean but I don't particular like it. My other thought is to have one table with columns for each custom data point for each client. This table would end up with a lot of columns and a lot of NULL values. I don't really like either solution and suspect there's a better way to do this, so any feedback you have will be appreciated.
I'm using SQL Server 2008.
As always with these questions, "it depends".
The dreaded key-value table.
This approach relies on a table which lists the fields and their values as individual records.
CustomFields(clientId int, fieldName sysname, fieldValue varbinary)
Benefits:
Infinitely flexible
Easy to implement
Easy to index
non existing values take no space
Disadvantage:
Showing a list of all records with complete field list is a very dirty query
The Microsoft way
The Microsoft way of this kind of problem is "sparse columns" (introduced in SQL 2008)
Benefits:
Blessed by the people who design SQL Server
records can be queried without having to apply fancy pivots
Fields without data don't take space on disk
Disadvantage:
Many technical restrictions
a new field requires DML
The xml tax
You can add an xml field to the table which will be used to store all the "extra" fields.
Benefits:
unlimited flexibility
can be indexed
storage efficient (when it fits in a page)
With some xpath gymnastics the fields can be included in a flat recordset.
schema can be enforced with schema collections
Disadvantages:
not clearly visible what's in the field
xquery support in SQL Server has gaps which makes getting your data a real nightmare sometimes
There are maybe more solutions, but to me these are the main contenders. Which one to choose:
key-value seems appropriate when the number of extra fields is limited. (say no more than 10-20 or so)
Sparse columns is more suitable for data with many properties which are filled out infrequent. Sounds more appropriate when you can have many extra fields
xml column is very flexible, but a pain to query. Appropriate for solutions that write rarely and query rarely. ie: don't run aggregates etc on the data stored in this field.
I'd suggest you go with the first option you described. I wouldn't over think it. The second option you outlined would be a bad idea in my opinion.
If there are fields common to all the modules you're adding to the system you should consider keeping those in a single table then have other tables with the fields specific to a particular module related back to the primary key in the common table. This is basically table inheritance (http://www.sqlteam.com/article/implementing-table-inheritance-in-sql-server) and will centralize the common module data and make it easier to query across modules.
This is a purely theoretical question (at least until I start trying to implement it) but here goes.
I wrote a web form a long time ago which has a configurable section for getting information. Basically for some customers there are no fields, for other customers there are up to 20 fields. I got it working by dynamically creating the fields at just the right time in the page lifecycle and going through a lot of headaches.
2 years later, I need to make some pretty big updates to this web form and there are some nifty new technologies. I've worked with ASP.NET Dynamic Data just a bit and, well, I half-crazed plan just occurred to me:
The Ticket object has a one-to-many relationship to ExtendedField, we'll call that relationship Fields for brevity.
Using that, the idea would be to create a FieldTemplate that dynamically generated the list of fields and displayed it.
The big questions here would probably be:
1) Can a single field template resolve to multiple web controls without breaking things?
2) Can dynamic data handle updating/inserting multiple rows in such a fashion?
3) There was a third question I had a few minutes ago, but coworkers interrupted me and I forgot. So now the third question is: what is the third question?
So basically, does this sound like it could work or am I missing a better/more obvious solution?
Did you try creating a FieldTemplate that had a "ListView" of all the Fields? (the ListView would use Dynamic Data to determine which FieldTemplate to display for each field.)
I don't see why this would not be possible. Although, "out of the box", you may have to hit "edit" on each row of the new FieldTemplate's ListView to edit the values. It would be like replacing the "Order Details" link in the Orders List, with an inline List of the "Order Details".
1.) Not very nicely. Can you imagine showing a DateTime, Integers, Phone numbers, Urls, etc with just ONE user control, like text.ascx? Why not have multiple field templates and use UIHint to specify usage per column?
2.) Yes.
3.) Define basically?
regarding one to many relationships, you might have a look at the ListDetails.aspx Page Template in Dynamic Data. Hope this helps.