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What is the difference between persist() and merge() in JPA and Hibernate?
...
Persist should be called only on new entities, while merge is meant to reattach detached entities.
If you're using the assigned generator, using merge instead of persist can cause a redundant SQL statement, therefore affecting performance.
A...
In Intellij, how do I toggle between camel case and underscore spaced?
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I use a plugin called String Manipulation which has the capabilities you're looking for (and more).
Select historyOfPresentIllness and press Alt+M to bring up the plugin menu, then press:
5 - To snake_case (or to camelCase) which conver...
How to change the foreign key referential action? (behavior)
...ess:
Suppose, a table1 has a foreign key with column name fk_table2_id, with constraint name fk_name and table2 is referred table with key t2 (something like below in my diagram).
table1 [ fk_table2_id ] --> table2 [t2]
First step, DROP old CONSTRAINT: (reference)
ALTER TABLE `t...
List of lists changes reflected across sublists unexpectedly
...s visible via all three references to it:
x = [1] * 4
l = [x] * 3
print(f"id(x): {id(x)}")
# id(x): 140560897920048
print(
f"id(l[0]): {id(l[0])}\n"
f"id(l[1]): {id(l[1])}\n"
f"id(l[2]): {id(l[2])}"
)
# id(l[0]): 140560897920048
# id(l[1]): 140560897920048
# id(l[2]): 140560897920048
x...
Linux bash: Multiple variable assignment
...otivation: What if ';' is a valid argument? When I write ls ; cd it still calls ls and cd despite the spaces. If I want to list directories called ; and cd I can just type ls ';' cd.
– PieterNuyts
Jul 18 '19 at 12:47
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Get the latest record from mongodb collection
...oDB are B-Trees. Searching a B-Tree is a O(logN) operation, so even find({_id:...}) will not provide constant time, O(1) responses.
That stated, you can also sort by the _id if you are using ObjectId for you IDs. See here for details. Of course, even that is only good to the last second.
You may t...
Post JSON using Python Requests
...rsion 2.4.2 and onwards, you can alternatively use 'json' parameter in the call which makes it simpler.
>>> import requests
>>> r = requests.post('http://httpbin.org/post', json={"key": "value"})
>>> r.status_code
200
>>> r.json()
{'args': {},
'data': '{"key": "...
How to inspect Javascript Objects
...e properties are not available for inspection, unless you use a "spy"; basically, you override the object and write some code which does a for-in loop inside the object's context.
For in looks like:
for (var property in object) loop();
Some sample code:
function xinspect(o,i){
if(typeof i==...
MySQL Error 1093 - Can't specify target table for update in FROM clause
...n case certain operations are carried out, merging cannot happen. E.g. provide the derived dummy table with a LIMIT (to inifity) and the error will never occur. That's pretty hackish though and there is still the risk that future versions of MySQL will support merging queries with LIMIT after all.
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Foreign Key to multiple tables
...on your needs.
You could simply create two columns in Ticket, OwnedByUserId and OwnedByGroupId, and have nullable Foreign Keys to each table.
You could create M:M reference tables enabling both ticket:user and ticket:group relationships. Perhaps in future you will want to allow a single ticket to ...