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I'd like to display a repeating event on a date/time display in an app. This date time display can take the form of a calendar, but it could also just be a list of upcoming events.
What is the best way to handle tracking this event that can repeat?
For example: Should the event be stored once in the database and projected out / repeated several times in the display code? Should the event be stored several times and then just rendered?
I did something like this before and I based my schema off of SQL Servers sysschedules table.
http://technet.microsoft.com/en-us/library/ms178644.aspx
The schema linked above will allow you to store the schedule for a job (event). Then you can calculate what dates the event occurs on based off of the schedule. This may be a lengthy calculation, so I would try to cache that result somewhere.
I think it depends on type of event it is. Is it like Christmas where once it comes along and happens you really aren't interested in it until the next occurrence? Or is it a task like, "Make sure I call my mom every month", where if it happens and you missed it you wouldn't want it to go away?
One way I recently implemented the latter was to have a record that had next_occurrence (date), reoccurence_period (weekly, monthly, yearly, etc) columns. So that as the next occurence approched it would show up in the list. Once it passed the list item would have a recycle icon that once pressed would update the record to the next future occurence.
Again, i'm not sure if this applies to your situation, but it worked well for mine.
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I am building an ASP.NET Core web app in C#. Clients can add an "inquiry" and the target response time is less than 30 minutes. Table "Inquiries" has many columns, among them: Id, Inquiry, and Reply.
Here is the scenario:
10h00: Client A adds an inquiry
10h09: No reply yet
10h10: Employee B gets notified that an inquiry has been added and has no reply yet
10h04: No reply yet
10h09: No reply yet
10h20: Employee B gets notified that an inquiry has been added and has no reply yet
10h21: Employee B adds reply and stops getting notified (B was getting notified every 10 minutes)
What would you say is the best approach to get this to work? I suppose I can write a C# function to check for empty "Reply" cells every 30 seconds, but I think it would exhaust memory when the database grows bigger, right? Can you point me in the right direction?
There are a few options here for this.
Personally, I would schedule an event in a secondary service to trigger tasks at a time window, but that may be overkill in your case.
Within your Inquiries, you (you probably already have this field) can use a last modified or last updated field to determine when this row was altered last via a calculation.
If you don't have a requirement of Source Control for your DB script, you can use stored procedures to manage this data and control the creating of these date/time stamps.
I would recommend updating your query to have a where clause on both the Last Updated time AND the null condition. This way there is no unnecessary records being processed and checked.
POST EDIT Alteration:
It seems like you have a creation date of events within the database, compare them to the current time on your retrieval query for determining an alert status.
About memory/performance impact:
The (C# application) memory impact will be based on the number of items returned, and not the number of items in the Database. So, if you add a where clause onto your query, you'll be able to ensure that the memory isn't allocated to misc. objects.
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I have a website dropdown that is populated from a SQL query. The values in the dropdown are from a table column and are like:
ABC-0123
ABC-0124
ABC-0125
ABC-0126.01
ABC-0126.02
ABC-0127
DEF-0123
DEF-0124
DEF-0125.1.01
DEF-0125.1.02
DEF-0125.2
I have a button to generate a new number based on what is selected in the dropdown. For example, if ABC-0125 is selected, ABC-0128 would need to be created since it's the next number in sequence. If ABC-0126.01 is selected, ABC-0126.03 would need to be created.
I'm looking for ideas on how to perform this. I considered just using the dropdown or querying the database directly.
I've split the selected value as a start:
String strDocFamily = drpDocFamily.SelectedValue;
string[] strDocTiers = strDocFamily.Split('.');
This may be open ended, but I'm looking for some suggestions on how to proceed. Thank you.
A solution might be to split the storage of the data into two or more columns, one for the alphabetic part ('ABC') another for the 'family' (0128 - the first set of digits) and others for the other tiers. You could then directly look up the maximum value of the 'family' column based on alphabetic. For example:
SELECT MAX(family-number)
FROM table-name
WHERE alpha-part='ABC';
Here is a UniqueID generator that can be easily adapted to generate a similar sequence to the one you need.
https://stackoverflow.com/a/39312025/2495728
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Today in the interview I faced a question tat I had no clue about. Being a newbie into ASP .Net MVC I had no other way but to ask the experts about it.
"In your MVC Application ,data are being stored into a RDBMS System. In a .cshtml page ,there is a button to update the existing records into DB.
Now suppose two users from different parts of the Globe are at the same time are trying to update a common record. But by the the time the second user hits the submit button, you already submitted the update. In that case the second user , when would be pressing the submit won't be able to submit. Instead the page would reloaded for the second user with the updated info, discarding the changes.And then only he would be able to go on with the update"
How could you achieve that in ASP .Net MVC?
I though thought it might be something from the DB Side coding also , but I have no clue how to achieve the same.
You need to implement a strategy for managing concurrency. How you do this depends largely on the business rules of the application and the type of conflict that arises when two or more people attempt to change the same record.
Most often, you will add a column called RowVersion which will be a timestamp type. Whenever you display records to be updated, you also select the current RowVersion value and usually store it in a hidden field. The update operation will include the RowVersion field, which gets a new value, but before you commit an update operation, you compare the RowVersion value you have with the current one in the database. If they are different, someone else has updated the row during the time that it took you to get the record to be updated and then tried to change it. You determine how to proceed based on the application's business rules.
Asynchronous Tasks do the database operations , so even if another user tries to update , the first process runs in the background asynchronously
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I want to read sms from my GSM modem.
I wrote C# code.
This code run when I click start button.
I want to my program read sms when received, not click button.
thanks.
Your program is keyed to activate when you press a button, some method is called. You need to call this method when SMS data is received instead. This could be done using threads (SMS thread and main thread showing data) although it could just as easily be done using a cycle. In pseudo code:
while (don't quit) {
display page;
check for sms data;
sleep for small time to allow other OS programs to run also;
}
This is a "tight loop" and can use excessive amounts of CPU time depending on the code of the actual steps. For a tight program loop one simple method is to apply some sort of sleep method.
There are other ways to do the same thing, visitor pattern could probably be used, threads, etc...
It seems that you are only lacking the cycle. Your programs is probably more like:
while (don't quit) {
display page.
wait for button press.
}
although that flow wouldn't be obviously apparent at first glance without studying your program flow.
If you are using triggers (the button press is probably a trigger) you can trigger on a timer that fires as often as you want (100ms, 1 second, whatever) that checks for SMS data when fired, if there is SMS data it updates the form.
Many, many ways to do this. A quick Google for "program flow" doesn't find any useful links at first glance that would explain the many ways you could do this. Perhaps looking at other's code would help. I've often searched open source repositories for code I could look at to see how someone else did something.
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i'm looking to implement a similar thing to stackoverflow badges. you could also equate them to achievements in games.
but am not sure how to design the database/code/tracking for them.
i get what i should do for badges such as:
Altruist × 1456 First bounty you manually awarded on another person's question
because they are a one time event, but how to handle others such as:
Analytical × 16389 Visited every section of the FAQ
Electorate × 1783 Voted on 600 questions and 25% or more of total votes are on questions
Outspoken × 188 Posted 10 messages in chat that were starred by 10 different users
etc...
how to handle them, how to keep track of progress for each, etc... is there a tutorial or something that can help me figure out a design pattern for them?
For the given examples, there are essentially two mechanisms you are going to need.
I don't know how it's done on SO, this is just a suggestion of a solution.
Let's look at 'Analytical' first. You are going to have to record by means of a simple flag when a user visits a particular area in the FAQ. Let's envisage a DB table with a field for each FAQ section and a user ID. This starts off as "N" (or 0, or however you want to represent your flag). When a user visits that area, you call code to flip that field to "Y". When all fields are "Y" then you can award that badge.
As for 'electorate' and 'Outspoken', you can retrieve this information by means of a query on your existing data, assuming the queries themseves are not too burdensome. You are going to need to consider when to run these checks. This essentially boils down to two options.
1) When the an action is performed that might get a badge awarded (i.e. visit section of FAQ, Vote on a Question, Question starred by someone else)
2) Periodically (hourly, daily, etc) run a check for all your badges against current data.
Bear in mind that badges are one-way in Stackoverflow, so if you are wanting to be equivalent then you don't have to consider logic to 'un-award' badges.