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What is the most efficient/elegant way to parse a flat table into a tree?
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Now that MySQL 8.0 supports recursive queries, we can say that all popular SQL databases support recursive queries in standard syntax.
WITH RECURSIVE MyTree AS (
SELECT * FROM MyTable WHERE ParentId IS NULL
UNION ALL
SELECT m.* FROM MyTABLE AS m JOIN MyTree AS t ON m.ParentI...
Remove all the elements that occur in one list from another
...have two lists, l1 and l2 . I want to perform l1 - l2 , which returns all elements of l1 not in l2 .
7 Answers
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What is a software framework? [closed]
...and again for the same type of applications, you create a framework having all those facilities together in one nice packet, hence providing the abstraction for your application and more importantly many applications.
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In Perl, how can I read an entire file into a string?
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before reading from the file handle. See How can I read in an entire file all at once?, or
$ perldoc -q "entire file"
See Variables related to filehandles in perldoc perlvar and perldoc -f local.
Incidentally, if you can put your script on the server, you can have all the modules you want. See ...
How can I get column names from a table in Oracle?
...u have 'no rows selected' then you could try to change USER_TAB_COLUMNS to all_tab_columns. To be 100% sure about result you could speficy owner.
– Dracontis
Feb 25 '15 at 9:01
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How to shrink/purge ibdata1 file in MySQL
...ng is a particularly annoying feature of MySQL. The ibdata1 file can't actually be shrunk unless you delete all databases, remove the files and reload a dump.
But you can configure MySQL so that each table, including its indexes, is stored as a separate file. In that way ibdata1 will not grow as la...
How to remove/delete a large file from commit history in Git repository?
I accidentally dropped a DVD-rip into a website project, then carelessly git commit -a -m ... , and, zap, the repo was bloated by 2.2 gigs. Next time I made some edits, deleted the video file, and committed everything, but the compressed file is still there in the repository, in history.
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UTF-8, UTF-16, and UTF-32
...ere UTF-16 remains at just 2 bytes for most characters.
UTF-32 will cover all possible characters in 4 bytes. This makes it pretty bloated. I can't think of any advantage to using it.
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impro...
Is it possible to import a whole directory in sass using @import?
...rails/sass-rails, features glob importing.
@import "foo/*" // import all the files in the foo folder
@import "bar/**/*" // import all the files in the bar tree
To answer the concern in another answer "If you import a directory, how can you determine import order? There's no way that doesn't...
Java Singleton and Synchronization
...e loaded when it is needed. That means that the first time getInstance is called, InstanceHolder will be loaded and instance will be created, and since this is controlled by ClassLoaders, no additional synchronization is necessary.
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