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How does database indexing work? [closed]
...arising from the file systems size limits, careful thought must be used to select the correct fields to index.
Since indices are only used to speed up the searching for a matching field within the records, it stands to reason that indexing fields used only for output would be simply a waste of disk...
How can I delete the current line in Emacs?
...lest way to delete (kill) a full line, from any point
on the line, without selecting anything, is:
C-w ; kill-region
It is versatile in deleting whatever is selected, or a line by default
if nothing is selected.
Given the question, you're probably also interested in replicating
Vim's "yank", yy...
How do I create a unique constraint that also allows nulls?
...dy found separately in other, properly defined columns. It should never be selected or used.
So, my story is that this is not a surrogate NULL, and I'm sticking to it! Since we don't actually want the non-NULL value for any purpose other than to trick the UNIQUE index to ignore NULLs, our use case ...
Getting and removing the first character of a string
...cters:
x <- 'hello stackoverflow'
substring(x, 2, nchar(x))
Idea is select all characters starting from 2 to number of characters in x. This is important when you have unequal number of characters in word or phrase.
Selecting the first letter is trivial as previous answers:
substring(x,1,1...
What is the difference between encode/decode?
...so the \u360 would be one character, not 5. Then you decode a string (with selected encoding) and get brand new object of the unicode type.
Just as a side note - you can select some pervert encoding, like 'zip', 'base64', 'rot' and some of them will convert from string to string, but I believe the ...
Table fixed header and scrollable body
...ad (e) {
const el = e.target,
sT = el.scrollTop;
el.querySelectorAll("thead th").forEach(th =>
th.style.transform = `translateY(${sT}px)`
);
}
document.querySelectorAll(".tableFixHead").forEach(el =>
el.addEventListener("scroll", tableFixHead)
);
...
Why java classes do not inherit annotations from implemented interfaces?
...nterface and I would like to annotate the interface methods so Guice could select the right methods. Even if the annotation type is annotated with Inherited annotation implementing class doesn't inherit the annotation as stated in Inherited's java doc:
...
doesn't inherit the font from
...does not inherit by default but you can set it to inherit with css
input, select, textarea, button{font-family:inherit;}
demo: http://jsfiddle.net/gaby/pEedc/1/
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MySQL Removing Some Foreign keys
...
You can use this to find foreign key constraints: SELECT * FROM information_schema.table_constraints WHERE constraint_schema = '<your db name>' AND constraint_type = 'FOREIGN KEY'
– Gayan Dasanayake
Aug 26 '17 at 2:48
...
how to set textbox value in jquery
...tched element.
You cannot set the value of a textbox with that method.
$(selector).load() returns the a jQuery object. By default an object is converted to [object Object] when treated as string.
Further clarification:
Assuming your URL returns 5.
If your HTML looks like:
<div id="foo"&g...