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How to add column if not exists on PostgreSQL?
...hich have no IF NOT EXISTS syntax - for example ALTER TABLE ... ADD CONSTRAINT.
– Tomasz Gandor
Apr 16 '19 at 9:51
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Safe characters for friendly url [closed]
...he question, you should only allow these characters:
Lower case letters (convert upper case to lower)
Numbers, 0 through 9
A dash - or underscore _
Tilde ~
Everything else has a potentially special meaning. For example, you may think you can use +, but it can be replaced with a space. & is ...
Build tree array from flat array in javascript
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For anyone interested, the code is easily converted to vanilla js: jsfiddle.net/LkkwH/853
– xec
Apr 12 '18 at 9:58
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CSS display: table min-height not working
...my footer where it should be. Works great in Chrome, but not FF or the PDf converter I'm using; wkhtmltopdf. Yes, height works, but doesn't mean the same thing semantically as min-height.
– rainabba
Feb 4 '16 at 1:54
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C# How can I check if a URL exists/is valid?
...e.g. images, files etc) HEAD usually works as advertised since it is baked into the server. Many programmers do not explicitly HEAD requests since the focus is normally on POST and GET. YMMV
– David Taylor
May 29 '09 at 15:53
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Is there any difference between a GUID and a UUID?
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Note that if you want to convert from Microsoft's GUID binary representation to a standard UUID you'll have to flip endianness of the first three (of four) data fields as detailed in the "Binary encoding" section here: en.wikipedia.org/wiki/Globally_...
Event handling for iOS - how hitTest:withEvent: and pointInside:withEvent: are related?
...*subview in [self.subviews reverseObjectEnumerator]) {
CGPoint convertedPoint = [subview convertPoint:point fromView:self];
UIView *hitTestView = [subview hitTest:convertedPoint withEvent:event];
if (hitTestView) {
return hitTestView;
}...
For loop for HTMLCollection elements
...bed above.
Update for ES6 in 2015
Added to ES6 is Array.from() that will convert an array-like structure to an actual array. That allows one to enumerate a list directly like this:
"use strict";
Array.from(document.getElementsByClassName("events")).forEach(function(item) {
console.log(item.i...
How to resume Fragment from BackStack if exists
...ment not in back stack, create it.
FragmentTransaction ft = manager.beginTransaction();
ft.replace(R.id.content_frame, fragment);
ft.addToBackStack(backStateName);
ft.commit();
}
}
EDIT
The problem is - when i launch A and then B, then press back button, B
is removed and ...
Primary key or Unique index?
...index on a column is an index on that column that also enforces the constraint that you cannot have two equal values in that column in two different rows. Example:
CREATE TABLE table1 (foo int, bar int);
CREATE UNIQUE INDEX ux_table1_foo ON table1(foo); -- Create unique index on foo.
INSERT INTO...