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Strings as Primary Keys in SQL Database [closed]
... wouldn't it depend on the database? I would think a properly indexed string would not be that much slower if at all from a number?
– Ryan Guill
Feb 5 '09 at 20:09
2
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How do I delete rows in a data frame?
...ven by the '-' operator" -> This is a very misleading wording. Negative indexes are removed and that's it, there is no notion of complement. If you work with logical and try using - it won't work, because the complement operator for logicals is !. The complement of c(2,4,6) in the rows would rath...
How can one see the structure of a table in SQLite? [duplicate]
...sqlite3.
Example:
sqlite> entropy:~/Library/Mail>sqlite3 Envelope\ Index
SQLite version 3.6.12
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> .tables
addresses ews_folders subjects
alarms feeds thr...
cartesian product in pandas
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Use pd.MultiIndex.from_product as an index in an otherwise empty dataframe, then reset its index, and you're done.
a = [1, 2, 3]
b = ["a", "b", "c"]
index = pd.MultiIndex.from_product([a, b], names = ["a", "b"])
pd.DataFrame(index = ...
How to use Elasticsearch with MongoDB?
...hrough many blogs and sites about configuring Elasticsearch for MongoDB to index Collections in MongoDB but none of them were straightforward.
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GIT: Checkout to a specific folder
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As per Do a "git export" (like "svn export")?
You can use git checkout-index for that, this is a low level command, if you want to export everything, you can use -a,
git checkout-index -a -f --prefix=/destination/path/
To quote the man pages:
The final "/" [on the prefix] is important. Th...
How can I get the corresponding table header (th) from a table cell (td)?
... $th = $td.closest('tbody').prev('thead').find('> tr > th:eq(' + $td.index() + ')');
Or a little bit simplified
var $th = $td.closest('table').find('th').eq($td.index());
share
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improve t...
Flatten an Array of Arrays in Swift
...ay.flatten(0, self)
}
public static func flatten<Element>(_ index: Int, _ toFlat: [Element]) -> [Element] {
guard index < toFlat.count else { return [] }
var flatten: [Element] = []
if let itemArr = toFlat[index] as? [Element] {
flatten = fl...
Is the NOLOCK (Sql Server hint) bad practice?
... IMO, This is a bit simplistic. Deadlocks can be removed by using covering indexes, taking the pressure off the Clustered index.
– Mitch Wheat
Sep 21 '09 at 6:27
8
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SQL Server SELECT LAST N Rows
...hout a sort of some nature this simply won't work, the best solution is to index the major columns being hit and run with something like the above query.
– JonVD
Nov 16 '10 at 23:15
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