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How to delete an old/unused Data Model Version in Xcode
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I tried this technique and found that due to the way my model versions were named, the model version were re-sorted improperly and the wrong default version was selected as I re-added the xcdatamodel file into the project. This may be because I am ...
Difference between timestamps with/without time zone in PostgreSQL
...g to the process of inserting/retrieving values. But readers should understand that both data types, timestamp with time zone and timestamp without time zone, in Postgres do *not actually store time zone information. You can confirm this with a glance at the data type doc page: Both types takes up t...
Are non-synchronised static methods thread safe if they don't modify static class variables?
...lity, etc.
This method only operates on parameters, which reside on stack and references to immutable objects on heap. Stack is inherently local to the thread, so no sharing of data occurs, ever.
Immutable objects (String in this case) are also thread-safe because once created they can't be change...
Using a BOOL property
...s used with heap allocated NSObjects like NSString*, NSNumber*, UIButton*, and etc, because memory managed accessors are created for free. When you create a BOOL, the value is always allocated on the stack and does not require any special accessors to prevent memory leakage. isWorking is simply th...
How to read a single char from the console in Java (as the user types it)?
...t you want to do is put the console into "raw" mode (line editing bypassed and no enter key required) as opposed to "cooked" mode (line editing with enter key required.) On UNIX systems, the 'stty' command can change modes.
Now, with respect to Java... see Non blocking console input in Python and ...
How to change the default collation of a table?
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To change the default character set and collation of a table including those of existing columns (note the convert to clause):
alter table <some_table> convert to character set utf8mb4 collate utf8mb4_unicode_ci;
Edited the answer, thanks to the prompt...
How to do an INNER JOIN on multiple columns
I'm working on a homework project and I'm supposed to perform a database query which finds flights either by the city name or the airport code, but the flights table only contains the airport codes so if I want to search by city I have to join on the airports table.
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Merging without whitespace conflicts
...'ve got a problem where I've got a large commit which changes about a thousand lines of code, removing whitespace from the end of lines and removing spaces before tabs.
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Why are ToLookup and GroupBy different?
...table with a billion rows in it?
The billion rows are sent over the wire, and you build the lookup table locally.
What happens when you call GroupBy on such an object?
A query object is built; end of story.
When that query object is enumerated then the analysis of the table is done on the databa...
jQuery - Get Width of Element when Not Visible (Display: None)
...: 0, outerWidth: 0, outerHeight: 0 },
$hiddenParents = $item.parents().andSelf().not(':visible'),
includeMargin = (includeMargin == null) ? false : includeMargin;
var oldProps = [];
$hiddenParents.each(function () {
var old = {};
for (var name in props) {
...