Is there a way to automatically delete a row 24 hours after its creation in Transact-SQL?
I'm making a site (learning experience) where the user needs to click a validation link sent by e-mail once they register. I want the users to validate themselves within 24 hours.
I suppose what I'd need is a trigger, but I'm really not sure on the syntax, nor if it is even possible.
I'm not sure of your schema but I would do it a different way. I would have a date/time against the database record that corresponds to the validation link. When they click the link, verify that the date and time of the database record is within 24 hours of the current time. If so, allow it, otherwise reject it.
Q: Is there a way to automatically delete a row 24 hours after its creation in Transact-SQL?
A: Sure. Write a "sqlcmd" script, wrap it in a .bat file, and invoke it from Windows Scheduled Tasks:
http://windows.microsoft.com/en-US/windows7/schedule-a-task
Alternatively, depending on your version, you could schedule the same SQL script from SQL Server Agent:
http://msdn.microsoft.com/en-us/library/ms189237.aspx
Putting a different spin on things:
When the user clicks your link, you can check if the current time (with respect to MSSQL) is >> 24 hours. If so, you'll reply with a "Too late" message (rather than validating the entry).
In any case - you absolutely, completely, totally, do NOT want to use a trigger!
Related
Hope I can explain the problem I'm having trouble with.
I have to write a stepwise methodology using pseudocode/SQL query to auto generate a list of products/items with low stock/expiry from the inventory database.The list must be updated at 12 a.m. daily.
I tried this
CREATE EVENT IF NOT EXISTS update_table
ON SCHEDULE EVERY 1 DAY STARTS '2022-05-22 00:00:00'
ON COMPLETION PRESERVE ENABLE
Do
Select inventory.products from inventory where inventory.stocks <
inventory.required_stocks.
Your stated requirement is to run some sort of report very soon after the beginning of each calendar day.
The next question you must answer is this: What will you do with that report? Will you simply drop it into "low_stock" table someplace in your database? Will you format it into an email message and send it to your purchasing department? It will be difficult to make "pseudocode" for your requirement without first analyzing the overall business process you intend to enhance.
Various RDBMS systems have ways of doing scheduled things at particular times of day. You've shown the EVENT setup provided by MariaDB / MySQL. SQL Server has their "Jobs" system. postgreSQL has the pg_cron extension. Yo
The thing is, you can't just do SELECT operations from within these scheduled database actions: the result sets have noplace to go from that context. You can do CREATE TABLE midnight_run AS SELECT whatever ... to place the results in a table. But then the results are in another table.
If you want to get the results out of the DBMS, you'll need a UNIXish cron job or a Windowsish scheduled task running an appropriate application at midnight each day.
Pro tip Do your best to avoid scheduling stuff for precisely midnight. Many things run then. If you wait until a couple of minutes after the hour, your code is less likely to contend with other midnight code.
I'm currently learning ABAP and trying to make an enhancement but have broken down in confusion on how to go about building on top of existing code. I have a program that runs periodically via a background job that disables user accounts X amount of days (in this case 90 days of inactive usage based on USR02~TRDAT).
I want to add an enhancement to notify the User via their email address (result of usr02~bname to match usr21~bname to pass the usr21~persnumber and usr21~addrnumber to adr6 which will point to the adr6~smtp_addr of the user, providing the usr02~bname -> adr6~smtp_addr relationship) based on their last logon date being 30, 15, 7, 5, 3, and 1 day away from the 90 day inactivity threshold with a link to the SAP system to help them reactivate the account with ease.
I'm beginning to think that an enhancement might not be a good idea but rather create a new program and schedule the background job daily. Any guidance or information would be greatly appreciated...
Extract
CLASS cl_inactive_users_reader DEFINITION.
PUBLIC SECTION.
TYPES:
BEGIN OF ts_inactive_user,
user_name TYPE syst_uname,
days_of_inactivity TYPE int1,
END OF ts_inactive_user.
TYPES tt_inactive_users TYPE STANDARD TABLE OF ts_inactive_user WITH EMPTY KEY.
CLASS-METHODS read_inactive_users
IMPORTING
min_days_of_inactivity TYPE int1
RETURNING
VALUE(result) TYPE tt_inactive_users.
ENDCLASS.
Then refactor
REPORT block_inactive_users.
DATA(inactive_users) = cl_inactive_users_readers=>read_inactive_users( 90 ).
LOOP AT inactive_users INTO DATA(inactive_user).
" block user
ENDLOOP.
And add
REPORT warn_inactive_users.
DATA(inactive_users) = cl_inactive_users_readers=>read_inactive_users( 60 ).
LOOP AT inactive_users INTO DATA(inactive_user).
CASE inactive_user-days_of_inactivity.
" choose urgency
ENDCASE.
" send e-mail
ENDLOOP.
and run both reports daily.
Don't create a big ball of mud by squeezing new features into existing code.
From SAP wiki:
The enhancement concept allows you to add your own functionality to SAP's standard business applications without having to modify the original applications. To modify the standard SAP behavior as per customer requirements, we can use enhancement framework.
As per your description, it doesn't sound like a use case for an enhancement. It isn't an intervention in an existing process. The original process and your new requirement are two different processes with some mutual logical part - selection of days of inactivity of users. The two shouldn't rely on each other.
Structurally I think it is best to have a separate program for computing which e-mails need to be sent and when, and a separate program for actually sending them.
I would copy your original program to a new one, and modify it a little bit so that instead of disabling a user, it records into some table for each user: 1) an e-mail 2) a date when to send 3) how many days left (30, 15, 7, etc) 4) status if the e-mail was sent or not. Initially you can even have multiple such jobs for each period (30, 15, 7 etc) and pass it as a parameter (which you use inside instead of 90).
This program you run daily as a job and it populates that table with e-mail "tasks" of what needs to be sent today. It just adds new lines, so lines from yesterday should stay in there.
The 2nd program should just read that table and send actual e-mails and update the statuses. You run that program daily as well.
This way you have:
overview: just check the table to see what's going on
control: if the e-mailer dies or hangs, you can restart it and it will continue where it left off; with statuses you avoid sending duplicate mails
you can make sure that you don't send outdated e-mails if in your mailer script you ignore all tasks older than say 2 days
I want to clarify your confusion about the use of enhancements:
You would want to use enhancements in terms of 'something' happens or is going to happen in the system and you would want to change this standard way.
That something, let's call it event or process could be for example an order is placed, a certain user is logging onto the system or a material has been or is going to be changed.
The change could be notifying another system of an order or checking the logged on user with additional checks for example his GUI version and warn him/her if not up-to-date.
Ask yourself, what process on the system does the execution of your program or code depend on. Does anything need to happen before the program is executed? No, only elapsing time.
Even if you had found an enhancement, you would want to use. If this process using the enhancement would not be run in 90 days, your mails would not be sent, because the enhancement would never been called.
edit: That being said, supposing you mean by enhancement 'building on your existing program' instead of 'creating a new one' would be absolutely not the right terminology for enhancement in the sap universe.
I would extend the functionality of your existing program, since you already compute how many days are left and you would have only one job to maintain.
I want to create a SQL Server table that has a Department and a Maximum Capacity columns (assume 10 for this scenario). When users add them selves to a department the system will check the current assignment count (assume 9 for this scenario) in the department and compare it to the maximum value. If it is below the maximum, they will be added.
The issue is this: what if two users submit at the same time and the when the code retrieves the current assignment count it will be 9 for both. One user updates the row sooner so now its 10 but the other user has already retrieved the previous value before the update (9) and so both are valid when compared and we end up with 11 users in the department.
Is this even possible and how can one solve it?
The answer to your problem lies in understanding "Database Concurrency" and then choosing the correct solution to your specific scenario.
It too large a topic to cover in a single SO answer so I would recommend doing some reading and coming back with specific questions.
However in simple form you either block the assignments out to the first person who tries to obtain them (pessimistic locking), or you throw an error after someone tries to assign over the limit (optimistic locking).
In the pessimistic case you then need ways to unblock them if the user fails to complete the transaction e.g. a timeout. A bit like on a ticket booking website it says "These tickets are being held for you for the next 10 minutes, you must complete your booking within that time else you may lose them".
And when you're down to the last few positions you are going to be turning everyone after the first away... no other way around it if you require this level of locking. (Well you could then create a waiting list, but that's another issue in itself).
Previously for my PHP app, I used a cron job that increments the health of a user in SQL every 10 minutes and the cron job script incremented the health of all users.
For my next app, I tried using MySQL events to increment the health every minutes for each individual user and ran into some problems with them not working after awhile (MySQL events stop working after awhile)
What's the best way to do this if I were to create a new app in Ruby on Rails? I'm open to using MySQL or PostgreSQL.
This is for a game where users will fight each other and lose health.
edit: Sometimes the user will encounter another user, and I need to select that user based on their health among other things. So I need the actual health stored in the database.
Instead updating every record in the database every 10 minutes, store a last-modified timestamp in the same row as the health. Every time you read the player_health from the database, add (current_time - last_modified) / (10 min) to the value. Every time you write player_health to the database, update the last_modified.
I would create a rake task that increases all users' health by 10, and call it using the awesome whenever gem every 10 minutes.
UPDATE
However, as Dan said in his comment, it might be inefficient to do such a huge DB update every 10 seconds (especially if you have huge number of users) if you can just update every user's health when he requests that. But that's subject to how your game actually works.
The correct fix, given a health bump of 10 points every minute, is a hitpoints variable and a timestamp for the last time it was set. Then the select statement will say "hitpoints + minutes(now - timestamp) * 10". Converting that to SQL is left as an exercise for the reader.
I like to think i'm not completely useless at creating MS Access databases, but i'm definitely a failure at the SQL code side.. So as a result i'm not sure whether this is a stupid question or not!
At work i'm trying to add a "news feed" type thing to a Form on the front screen of a database used to find useful information stored in various places. At the moment my workplace is using Office 2007, but Access is the 97 version!!!! As they're only recently realizing it can be used to solve a few of their problems... we're expecting to upgrade the whole of office and access to 2010 soon.
On this database (created using access 97..) there is a "refresh" type button which simply closes and re-opens the form and thus shows the latest info entered onto the "news feed", and this also shows the current time and date. What i'd like to happen is have specific entries drop off after a period of time (which probably wont happen unless refreshed), so for example an entry will have been added regarding some server ammendments being made within the workplace so "certain systems will not be working between 8am and 5pm GMT on 9/1/12" and preferably the person who created this entry could enter a date into the form 24 hours, or even a few days, later and when this date is reached the entry would disappear. I understand this is something that may be achieved using a query but i have no idea where to start.
If anyone can help give me an idea of how to do this it would be greatly appreciated.
I apologise if this is poorly worded or not completely clear, i can elaborate if questions are asked.
many thanks,
Kris
You can make a query like this to return only the entries that are less than 3 days old:
SELECT *
FROM MyTable
WHERE CreateTime > DateAdd("d", -3, Now())
In your form, you can define a timer interval and a timer event handler (see the "Event" tab on the properties window). You could use it to requery your list (Me!lstNews.Requery).
In the table you can define the column "CreateTime" as data type "Date/Time" and define its default value as =Now(). This way no text box is required to enter this data.
EDIT:
How to configure the timer in an Access Form (time is in milliseconds):