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SQL UPDATE SET one column to be equal to a value in a related table referenced by a different column
...QuestionAnswers a
on q.AnswerID = a.AnswerID
where q.QuestionID is null -- and other conditions you might want
I recommend to check what the result set to update is before running the update (same query, just with a select):
select *
from QuestionTrackings q
inner join QuestionAnswers a
on q.Answ...
Confusion: @NotNull vs. @Column(nullable = false) with JPA and Hibernate
...tation of JSR 303, however, it intelligently picks up on these constraints and translates them into database constraints for you, so you get two for the price of one. @Column(nullable = false) is the JPA way of declaring a column to be not-null. I.e. the former is intended for validation and the lat...
Cannot create an NSPersistentStoreCoordinator with a nil model
Been having my first crack at Core Data and I'm getting the following error when running my code on my device, but it works fine on the simulator..
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How do you log server errors on django sites
...hen playing with the development I can just set settings.DEBUG to True and if an error occures I can see it nicely formatted, with good stack trace and request information.
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How to set size for local image using knitr for markdown?
...ge that I would like to include in an .Rmd file which I will then knit and convert to HTML slides with Pandoc . Per this post , this will insert the local image :
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List of foreign keys and the tables they reference
...o find a query which will return me a list of the foreign keys for a table and the tables and columns they reference. I am half way there with
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Can I use the range operator with if statement in Swift?
Is it possible to use the range operator ... and ..< with if statement. Maye something like this:
6 Answers
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Using Transactions or SaveChanges(false) and AcceptAllChanges()?
I have been investigating transactions and it appears that they take care of themselves in EF as long as I pass false to SaveChanges() and then call AcceptAllChanges() if there are no errors:
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node.js child process - difference between spawn & fork
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Spawn is a command designed to run system commands. When you run spawn, you send it a system command that will be run on its own process, but does not execute any further code within your node process. You can add listeners for the proces...
What is an NP-complete in computer science?
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NP stands for Non-deterministic Polynomial time.
This means that the problem can be solved in Polynomial time using a Non-deterministic Turing machine (like a regular Turing machine but also including a non-deterministic "choice"...