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How to implement a many-to-many relationship in PostgreSQL?
...the name of a product is hardly unique (not a good "natural key"). Also, enforcing uniqueness and referencing the column in foreign keys is typically cheaper with a 4-byte integer (or even an 8-byte bigint) than with a string stored as text or varchar.
Don't use names of basic data types like date ...
How to get the currently logged in user's user id in Django?
...henticated, like so:
if request.user.is_authenticated:
# Do something for authenticated users.
else:
# Do something for anonymous users.
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How can I get LINQ to return the object which has the max value for a given property? [duplicate]
...
.OrderByDescending(i=>i.id).Take(1)
Regarding the performance concern, it is very likely that this method is theoretically slower than a linear approach. However, in reality, most of the time we are not dealing with the data set that is big enough to make any difference.
If pe...
Django optional url parameters
...foo),
)
Keep in mind that in your view you'll also need to set a default for the optional URL parameter, or you'll get an error:
def foo(request, optional_parameter=''):
# Your code goes here
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Insert Update stored proc on SQL Server
...lled upsert/merge.
Importance of UPSERT - from sqlservercentral.com:
For every update in the case mentioned above we are removing one
additional read from the table if we
use the UPSERT instead of EXISTS.
Unfortunately for an Insert, both the
UPSERT and IF EXISTS methods use the
same...
How to get the insert ID in JDBC?
...it is an auto generated key, then you can use Statement#getGeneratedKeys() for this. You need to call it on the same Statement as the one being used for the INSERT. You first need to create the statement using Statement.RETURN_GENERATED_KEYS to notify the JDBC driver to return the keys.
Here's a b...
MySQL select one column DISTINCT, with corresponding other columns
...practice I've successfully used this kind of queries with ORDER BY clause, for instance you could add ORDER BY id ASC/DESC and MySQL would return consistent results every time you would execute the query. But i would be sure whether anyone should use undocumented features in production environment.
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How to Store Historical Data
... I got into a debate on the best way to store historical data. Currently, for some systems, I use a separate table to store historical data, and I keep an original table for the current, active record. So, let's say I have table FOO. Under my system, all active records will go in FOO, and all his...
Move to another EditText when Soft Keyboard Next is clicked on Android
...p="@+id/.."
Besides directional navigation you can use tab navigation. For this you need to use
android:nextFocusForward="@+id/.."
To get a particular view to take focus, call
view.requestFocus()
To listen to certain changing focus events use a View.OnFocusChangeListener
Keyboard butto...
Bold words in a string of strings.xml in Android
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For anybody else who found the official Android documentation a bit too vague on this: if you use tags like <b> in your string resource, make sure you retrieve it using getText(R.string.whatever) rather than getString(R...