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Checking for an empty field with MySQL
...e range access if you have lots of empty email record (both types) in your table.
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Understanding “randomness”
...et after multiplying two random variables:
BarChart[BinCounts[Table[RandomReal[{0, 1}, 50000] *
RandomReal[{0, 1}, 50000], {50000}], 0.01]]
So, both are “random”, but their distribution is very different.
Another example
While 2 * Random() is un...
Escape string for use in Javascript regex [duplicate]
...d-to-test voodoo.
var escapeRegExp;
(function () {
// Referring to the table here:
// https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/regexp
// these characters should be escaped
// \ ^ $ * + ? . ( ) | { } [ ]
// These characters only have special meaning inside of b...
How efficient is locking an unlocked mutex? What is the cost of a mutex?
... system limit. But too many of them spells nightmare for debugging. Simple table:
Less locks means more contentions (slow syscalls, CPU stalls) and lesser parallelism
Less locks means less problems debugging multi-threading problems.
More locks means less contentions and higher parallelism
More lo...
How big can a user agent string get?
...
My take on this:
Use a dedicated table to store only UserAgents (normalize it)
In your related tables, store an Foreign Key value to point back to the UserAgent auto-increment primary key field
Store the actual UserAgent string in a TEXT field and care not a...
How to limit UITableView row reordering to a section
...ing on where the drag went, instead of where it started.
- (NSIndexPath *)tableView:(UITableView *)tableView targetIndexPathForMoveFromRowAtIndexPath:(NSIndexPath *)sourceIndexPath toProposedIndexPath:(NSIndexPath *)proposedDestinationIndexPath
{
if (sourceIndexPath.section != proposedDestination...
Is it safe to parse a /proc/ file?
...s even less consistent than that. It's atomic only within each row of the table. To see this, look at listening_get_next() in net/ipv4/tcp_ipv4.c and established_get_next() just below in the same file, and see the locks they take out on each entry in turn. I don't have repro code handy to demonst...
Disable spell-checking on HTML textfields
...
MDN has a table showing the default value of spellcheck for different browsers and elements: developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/…
– Paul
Jan 31 '17 at 17:39
...
How to extract text from a PDF? [closed]
...
I was given a 400 page pdf file with a table of data that I had to import - luckily no images. Ghostscript worked for me:
gswin64c -sDEVICE=txtwrite -o output.txt input.pdf
The output file was split into pages with headers, etc., but it was then easy to write a...
Ordering by the order of values in a SQL IN() clause
...inputted by the query in MS SQL Server 2008+, it can be done by creating a table on the fly and doing a join like so (using nomenclature from OP).
SELECT table1.name, table1.description ...
FROM (VALUES (id1,1), (id2,2), (id3,3) ...) AS orderTbl(orderKey, orderIdx)
LEFT JOIN table1 ON orderTbl.or...