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What is the difference between String.slice and String.substring?
...te #3:slice()==substring()
Using Negative Numbers as an Argument:
slice() selects characters starting from the end of the string
substr()selects characters starting from the end of the string
substring() Doesn't Perform
Note #3:slice()==substr()
if the First Argument is Greater than the Second:
sl...
Using psql how do I list extensions installed in a database?
...org/docs/current/static/app-psql.html
Doing it in plain SQL it would be a select on pg_extension:
SELECT *
FROM pg_extension
http://www.postgresql.org/docs/current/static/catalog-pg-extension.html
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How to replace four spaces with a tab in Sublime Text 2?
...er), ensure it says Tab Width: 4 for converting from four spaces, and then select Convert Indentation to Tabs from the contextual menu that will appear from the initial click.
Similarly, if you want to do the opposite, click the Spaces or Tab Width text on the status bar and select from the same me...
What Does Question Mark Mean in Xcode Project Navigator?
...
You can add to source control by selecting the untracked files
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autolayout - make height of view relative to half superview height
...lso need to setup bottom, left, and right constraints, like normal)
. Then select the constraint and navigate to the Attribute inspector:
Then you can adjust the multiplier. If you want it 50% of the super view leave it at 1, since it is aligned per the super's center. This is also a great way to...
querySelector search immediate children
...
Though it's not a full answer, you should keep an eye on the W3C Selector API v.2 which is already available in most browser, both desktop and mobile, except IE (Edge seems to support): see full support list.
function(elem) {
return elem.querySelectorAll(':scope > someselector');
};
...
How do I use installed packages in PyCharm?
...er's path. It will bring up a short drop-down menu, from which you should select "More..". On the right hand side of the new pop-up, there will be an icon with the mouse-over text of "Show paths for the selected interpreter". Click that button. This new 'Interpreter Paths' pop-up is where you ca...
How can I check MySQL engine type for a specific table?
...st of all the tables in a database and their engines, use this SQL query:
SELECT TABLE_NAME,
ENGINE
FROM information_schema.TABLES
WHERE TABLE_SCHEMA = 'dbname';
Replace dbname with your database name.
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Best way to check for “empty or null value”
... '
Demo
Empty string equals any string of spaces when cast to char(n):
SELECT ''::char(5) = ''::char(5) AS eq1
, ''::char(5) = ' '::char(5) AS eq2
, ''::char(5) = ' '::char(5) AS eq3;
Result:
eq1 | eq2 | eq3
----+-----+----
t | t | t
Test for "null or empty string" w...
Overriding a Rails default_scope
...ed_at desc')
end
Foo.reorder('created_at asc')
runs the following SQL:
SELECT * FROM "foos" ORDER BY created_at asc
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