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Difference between EXISTS and IN in SQL?
... as a way to avoid counting:
--this statement needs to check the entire table
select count(*) from [table] where ...
--this statement is true as soon as one match is found
exists ( select * from [table] where ... )
This is most useful where you have if conditional statements, as exists can be ...
How to select a single field for all documents in a MongoDB collection?
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get all data from table
db.student.find({})
SELECT * FROM student
get all data from table without _id
db.student.find({}, {_id:0})
SELECT name, roll FROM student
get all data from one field with _id
db.student.find({}, {ro...
how to make a whole row in a table clickable as a link?
...like this (in a document.ready callback):
$("#container").on('click-row.bs.table', function (e, row, $element) {
window.location = $element.data('href');
});
This has the advantage of not being reset upon table sorting (which happens with the other option).
Note
Since this was posted window.do...
What is the dual table in Oracle?
I've heard people referring to this table and was not sure what it was about.
14 Answers
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Using R to download zipped data file, extract, and import data
...oad.file("http://www.newcl.org/data/zipfiles/a1.zip",temp)
data <- read.table(unz(temp, "a1.dat"))
unlink(temp)
Compressed (.z) or gzipped (.gz) or bzip2ed (.bz2) files are just the file and those you can read directly from a connection. So get the data provider to use that instead :)
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Delete/Reset all entries in Core Data?
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You can delete the SQLite file - but I choose to do it by purging the tables individually with a functions:
- (void) deleteAllObjects: (NSString *) entityDescription {
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription enti...
Table Naming Dilemma: Singular vs. Plural Names [closed]
Academia has it that table names should be the singular of the entity that they store attributes of.
41 Answers
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How does C compute sin() and other math functions?
...ximations for both sin(x) and cos(x), then using values from a precomputed table to refine the approximation.
When |x| > 2, none of the above algorithms would work, so the code starts by computing some value closer to 0 that can be fed to sin or cos instead.
There's yet another branch to deal wit...
MySQL Cannot Add Foreign Key Constraint
... as a project requirement and it worked the first time or two on different tables, but I have two tables on which I get an error when trying to add the Foreign Key Constraints.
The error message that I get is:
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MySQL offset infinite rows
I would like to construct a query that displays all the results in a table, but is offset by 5 from the start of the table. As far as I can tell, MySQL's LIMIT requires a limit as well as an offset. Is there any way to do this?
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