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Understanding Python's “is” operator
...ation for the is operator:
The operators is and is not test for object identity: x is y is true if and only if x and y are the same object.
Use the == operator instead:
print(x == y)
This prints True. x and y are two separate lists:
x[0] = 4
print(y) # prints [1, 2, 3]
print(x == y) # p...
SQL Joins Vs SQL Subqueries (Performance)?
...vary. The speed will depend a lot on indexes (do you have indexes on both ID columns? That will help a lot...) among other things.
The only REAL way to tell with 100% certainty which is faster is to turn on performance tracking (IO Statistics is especially useful) and run them both. Make sure to...
how to exclude null values in array_agg like in string_agg using postgres?
...
SQL Fiddle
select
id,
(select array_agg(a) from unnest(canonical_users) a where a is not null) canonical_users,
(select array_agg(a) from unnest(non_canonical_users) a where a is not null) non_canonical_users
from (
...
Possibility of duplicate Mongo ObjectId's being generated in two different collections?
Is it possible for the same exact Mongo ObjectId to be generated for a document in two different collections? I realize that it's definitely very unlikely, but is it possible?
...
How can I pass selected row to commandLink inside dataTable or ui:repeat?
...ws, I want the user to be able to directly execute various actions on individual rows. For that, I have several <p:commandLink> s in the last column.
...
How to do this in Laravel, subquery where in
...
Consider this code:
Products::whereIn('id', function($query){
$query->select('paper_type_id')
->from(with(new ProductCategory)->getTable())
->whereIn('category_id', ['223', '15'])
->where('active',...
Patterns for handling batch operations in REST web services?
...ource. For example, to delete several messages at once.
DELETE /mail?&id=0&id=1&id=2
It's a little more complicated to batch update partial resources, or resource attributes. That is, update each markedAsRead attribute. Basically, instead of treating the attribute as part of each reso...
How do I link to part of a page? (hash?)
...
If there is an <a name="foo"> tag or any tag with an id (e.g., <div id="foo">), then you can simply append #foo to the URL. Otherwise, you can't arbitrarily link to portions of a page.
Here's a complete example: <a href="http://example.com/page.html#foo">Jump to #...
How to continue a Docker container which has exited
Consider:
10 Answers
10
...
SQL select only rows with max value on a column [duplicate]
...All you need is a GROUP BY clause with the MAX aggregate function:
SELECT id, MAX(rev)
FROM YourTable
GROUP BY id
It's never that simple, is it?
I just noticed you need the content column as well.
This is a very common question in SQL: find the whole data for the row with some max value in a co...