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What's the difference between NOT EXISTS vs. NOT IN vs. LEFT JOIN WHERE IS NULL?
... NULL is less efficient
In PostgreSQL, NOT IN is less efficient
In Oracle, all three methods are the same.
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Get application version name using adb
...y package I have tried to look up on my tablet (android 2.2). On my phone all the version information is there (android 2.3).
– frognosis
Aug 13 '12 at 23:08
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MySQL 'create schema' and 'create database' - Is there any difference
... CREATE SCHEMA is a synonym for CREATE DATABASE as of MySQL 5.0.2.
this all goes back to an ANSI standard for SQL in the mid-80s.
That standard had a "CREATE SCHEMA" command, and it served to introduce
multiple name spaces for table and view names. All tables and views were
created within a "s...
Differences between Java 8 Date Time API (java.time) and Joda-Time
...s perfect ;-)).
c) With both libraries we get a real calendar date type (called LocalDate), a real wall time type (called LocalTime) and the composition (called LocalDateTime). That is a very big win compared with old java.util.Calendar and java.util.Date.
d) Both libraries use a method-centric ap...
Convert to absolute value in Objective-C
...), fabsf(float), fabs(double), or fabsl(long double).
Those functions are all part of the C standard library, and so are present both in Objective-C and plain C (and are generally available in C++ programs too.)
(Alas, there is no habs(short) function. Or scabs(signed char) for that matter...)
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“git pull” or “git merge” between master and development branches
...nges. I need to merge changes from master into develop , but will eventually merge everything from develop into master . I have two different workflows in mind:
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When to use , tag files, composite components and/or custom components?
...nces be the only solution when a composite component doesn't suffice. Generally, having an <ui:include> with one or more <ui:param> which passes a managed bean property (and thus not a hardcoded value) is a signal that the include file can better be a tag file.
Examples:
How to create a...
isset() and empty() - what to use
... check - is variable empty or contains something. To solve this task, I usually do the following.
6 Answers
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MongoDB: How to query for records where field is null or not set?
...ount({sent_at: {$exists: false}})
If its there and null, or not there at all:
db.emails.count({sent_at: null})
Refer here for querying and null
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Does every Javascript function have to return a value?
...ow level, the return is translated into some sort of jump. If a function really returned nothing at all, there would be no way of knowing what and when to call the next function, or to call event handlers and the like.
So to recap: No, a JS function needn't return anything as far as your code goes....