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Can hash tables really be O(1)?
It seems to be common knowledge that hash tables can achieve O(1), but that has never made sense to me. Can someone please explain it? Here are two situations that come to mind:
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SQL Joins Vs SQL Subqueries (Performance)?
...ies with Semijoin Transformations
Rewriting Subqueries as Joins
I have a table with 50000 elements, the result i was looking for was 739 elements.
My query at first was this:
SELECT p.id,
p.fixedId,
p.azienda_id,
p.categoria_id,
p.linea,
p.tipo,
p.nome
FROM prodotto p
WH...
Does MySQL index foreign key columns automatically?
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Yes, but only on innodb. Innodb is currently the only shipped table format that has foreign keys implemented.
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LEFT JOIN vs. LEFT OUTER JOIN in SQL Server
... at the answer I left on this other SO question: SQL left join vs multiple tables on FROM line?.
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How do I set a background-color for the width of text, not the width of the entire element, using CS
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display:table is a better choice... to avoid the problem highlighted in the comments section in the next reply. display:inline will concatenate <h1> and <h2> to be in same line.... when they are originally in next lines.
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Exporting data In SQL Server as INSERT INTO
I am using SQL Server 2008 Management Studio and have a table I want to migrate to a different db server.
11 Answers
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How to sort a dataframe by multiple column(s)
...ices
order from base
arrange from dplyr
setorder and setorderv from data.table
arrange from plyr
sort from taRifx
orderBy from doBy
sortData from Deducer
Most of the time you should use the dplyr or data.table solutions, unless having no-dependencies is important, in which case use base::order.
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Example JavaScript code to parse CSV data
...;
var chars = csv.split(''), c = 0, cc = chars.length, start, end, table = [], row;
while (c < cc) {
table.push(row = []);
while (c < cc && '\r' !== chars[c] && '\n' !== chars[c]) {
start = end = c;
if ('"'...
jQuery - Get Width of Element when Not Visible (Display: None)
... visible width() returns 0. Makes sense, but I need to get the width of a table in order to set the width of the parent before I show the parent.
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Django-DB-Migrations: cannot ALTER TABLE because it has pending trigger events
...s at the django shell. If you're looking for something more formal and testable, it depends on what versions you're using. If you use south, see: south.readthedocs.org/en/latest/tutorial/part3.html and if you use django's migrations, see the "data migrations" section here: docs.djangoproject.com/e...