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Remove all special characters with RegExp
...
The caret (^) character is the negation of the set [...], gi say global and case-insensitive (the latter is a bit redundant but I wanted to mention it) and the safelist in this example is digits, word characters, underscores (\w) and whitespace (\s).
...
Convert RGB to RGBA over white
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Take the lowest color component, and convert that to an alpha value. Then scale the color components by subtracting the lowest, and dividing by the alpha value.
Example:
152 converts to an alpha value of (255 - 152) / 255 ~ 0.404
152 scales using (152 - 1...
How do I perform an IF…THEN in an SQL SELECT?
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The CASE statement is the closest to IF in SQL and is supported on all versions of SQL Server.
SELECT CAST(
CASE
WHEN Obsolete = 'N' or InStock = 'Y'
THEN 1
ELSE 0
END AS bit) as Saleable,...
Pipe to/from the clipboard in Bash script
... has a utility that lets you talk to it.
In the case of X, there's xclip (and others). xclip -selection c will send data to the clipboard that works with Ctrl + C, Ctrl + V in most applications.
If you're on Mac OS X, there's pbcopy. e.g cat example.txt | pbcopy
If you're in Linux terminal mode (...
How to quickly and conveniently create a one element arraylist [duplicate]
...ariable size List
If it needs vary in size you can construct an ArrayList and the fixed-sizeList like
return new ArrayList<String>(Arrays.asList(s));
and (in Java 7+) you can use the diamond operator <> to make it
return new ArrayList<>(Arrays.asList(s));
Single Element Lis...
When should I use Write-Error vs. Throw? Terminating vs. non-terminating errors
...It does not stop a pipeline or a loop from continuing. Throw on the other hand produces what is called a terminating error. If you use throw, the pipeline and/or current loop will be terminated. In fact all execution will be terminated unless you use a trap or a try/catch structure to handle the ter...
Why is it string.join(list) instead of list.join(string)?
...e any iterable can be joined (e.g, list, tuple, dict, set), but the result and the "joiner" must be strings.
For example:
'_'.join(['welcome', 'to', 'stack', 'overflow'])
'_'.join(('welcome', 'to', 'stack', 'overflow'))
'welcome_to_stack_overflow'
Using something else than strings will raise t...
How do I restore a dump file from mysqldump?
...many databases, the use statements are already in there.
To run these commands, open up a command prompt (in Windows) and cd to the directory where the mysql.exe executable is (you may have to look around a bit for it, it'll depend on how you installed mysql, i.e. standalone or as part of a package...
Why doesn't a python dict.update() return the object?
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Python's mostly implementing a pragmatically tinged flavor of command-query separation: mutators return None (with pragmatically induced exceptions such as pop;-) so they can't possibly be confused with accessors (and in the same vein, assignment is not an expression, the statement-expressi...
How to get ID of the last updated row in MySQL?
...T 1;
SELECT @update_id;
EDIT by aefxx
This technique can be further expanded to retrieve the ID of every row affected by an update statement:
SET @uids := null;
UPDATE footable
SET foo = 'bar'
WHERE fooid > 5
AND ( SELECT @uids := CONCAT_WS(',', fooid, @uids) );
SELECT @uids;
This w...