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COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better? [duplicate]
...SELECT count(*) FROM my_table to "return the table count", which is has on file. For queries with WHERE clauses, InnoDB and MyISAM function the same.
– Joel Mellon
Feb 5 '16 at 16:54
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Can't pickle when using multiprocessing Pool.map()
... for object 0x...: pointer being freed was not allocated (e.g. open member file) or pure virtual method called,
terminate called without an active exception (which means than the lifetime of a member object I used was shorter than what I thought). I got this when dealing with n greater than the pool...
How do DATETIME values work in SQLite?
...ntegers.
Integers will always be supported as integers in databases, flat files, etc. You do a little math and cast it into another type and you can format the date anyway you want.
Doing it this way, you don't have to worry when [insert current favorite database here] is replaced with [future ...
Why is using a wild card with a Java import statement bad?
...on all classes. There is nothing more disconcerting than opening a source file and having to page through 100 import statements.
Doing specific imports makes refactoring more difficult; if you remove/rename a class, you need to remove all of its specific imports. If you switch an implementation t...
What is the difference between DAO and Repository patterns?
...ou persist it (e.g. imagine you'll need a DAO that stores your data in XML files or gets it from a message queue rather than from Database ...).
– Stef
Mar 20 '13 at 0:15
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Why use getters and setters/accessors?
...ter from the getter".
So, now that you broke the contract, changing every file in the codebase is something you should want to do, not avoid. If you avoid it you're making the assumption that all the code assumed the contract for those methods was different.
If that should not have been the contra...
What is the difference between integration and unit tests?
...s still a unit test, but once you test for both I/O AND the content of the file, then you have yourself an integration test. When you test the output of a function within a service, it's a unit-test, but once you make a service call and see if the function result is the same, then that's an integrat...
What is the difference between public, protected, package-private and private in Java?
...ring and used as a hook in subclasses should be protected.
A void saveGame(File dst) method which is called from the GUI code should be public.
(*) What is Encapsulation exactly?
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Curly braces in string in PHP
... = $wpdb->get_results("select * from {$wpdb->prefix}download_monitor_files");
This is really handy technique for formatting complex strings.
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Convert columns to string in Pandas
...on()
Out[13]: '{"0":"A","1":"A","2":"B"}'
Note: you can pass in a buffer/file to save this to, along with some other options...
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