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MySQL - UPDATE query based on SELECT Query
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You can actually do this one of two ways:
MySQL update join syntax:
UPDATE tableA a
INNER JOIN tableB b ON a.name_a = b.name_b
SET validation_check = if(start_dts > end_dts, 'VALID', '')
-- where clause can go here
ANSI SQL syntax...
Is there a performance difference between i++ and ++i in C++?
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However, if i is an instance of a C++ class, then i++ and ++i are making calls to one of the operator++ functions. Here's a standard pair of these functions:
Foo& Foo::operator++() // called for ++i
{
this->data += 1;
return *this;
}
Foo Foo::operator++(int ignored_dummy_value) ...
How to get position of a certain element in strings vector, to use it as an index in ints vector?
...e use size_t we must be careful not to subtract a larger iterator from a smaller iterator.
– dasblinkenlight
Oct 17 '17 at 10:49
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Simulate CREATE DATABASE IF NOT EXISTS for PostgreSQL?
...an work around it from within psql by executing the DDL statement conditionally:
SELECT 'CREATE DATABASE mydb'
WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = 'mydb')\gexec
The manual:
\gexec
Sends the current query buffer to the server, then treats each column of each row of the query's...
Determine what attributes were changed in Rails after_save callback?
I'm setting up an after_save callback in my model observer to send a notification only if the model's published attribute was changed from false to true. Since methods such as changed? are only useful before the model is saved, the way I'm currently (and unsuccessfully) trying to do so is as fol...
Passing base64 encoded strings in URL
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edited Jul 17 '17 at 14:16
ArchimedesMP
26011 silver badge88 bronze badges
answered Apr 29 '11 at 17:3...
What's the best way to inverse sort in scala?
...Int].reverse) also.
– dtech
May 18 '16 at 13:15
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show 1 m...
No route matches [GET] /assets
...nment. I ran RAILS_ENV=production rake assets:precompile which generated all of my assets in /public/assets. The problem is that when I start my app w/ RAILS_ENV=production rails s thin I get:
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How to set Oracle's Java as the default Java in Ubuntu?
...of the JVM, you don't need to update your .bashrc file, it should automatically point to the new version.
If you want to set JAVA_HOME environment variables globally and at system level means use should set in /etc/environment file.
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What is SYSNAME data type in SQL Server?
...les.
– gloomy.penguin
Mar 26 '13 at 16:10
3
@Barry Actually... according to sys.types it's a nvar...