大约有 40,000 项符合查询结果（耗时：0.0309秒） [XML]
Count(*) vs Count(1) - SQL Server
...utation intensive function.
In my test database, t_even is a table with 1,000,000 rows
This query:
SELECT COUNT(SYS_GUID())
FROM t_even
runs for 48 seconds, since the function needs to evaluate each SYS_GUID() returned to make sure it's not a NULL.
However, this query:
SELECT COUNT(*)
FR...
Display JSON as HTML [closed]
... value: "#ff0"
},
{
color: "black",
value: "#000"
}
]
</code>
</pre>
</body>
</html>
Otherwise I would use JSON Viewer.
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machine learning libraries in C# [closed]
...meworks listed, Accord.NET is open-source and the most popular with over 2,000 stars.
Also, check out the official machine learning library for .NET provided by Microsoft: https://github.com/dotnet/machinelearning
OLD
There's a neural network library called AForge.net on the codeproject. (Code ...
Select multiple records based on list of Id's with linq
...id, (up, id) => up);
And now result of my measurement. I generated 100 000 UserProfiles and 100 000 ids. Join took 32ms and .Where with .Contains took 2 minutes and 19 seconds! I used pure IEnumerable for this testing to prove my statement. If you use List instead of IEnumerable, .Where and .Con...
Edit line thickness of CSS 'underline' attribute
...on:absolute;
left:0;
bottom:0;
right:0;
margin:auto;
background:#000;
height:1px;
}
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How to get the data-id attribute?
...so doesn't change the value's representation. For example, "1E02" and "100.000" are equivalent as numbers (numeric value 100) but converting them would alter their representation so they are left as strings. "
– Wesley Murch
Mar 29 '14 at 4:29
...
Is “double hashing” a password less secure than just hashing it once?
... list is less than three hours if only one iteration is used. But if just 2000 iterations are used, that time extends to almost 8 months. To defeat a more sophisticated attacker—one capable of downloading a program that can tap the power of their GPU, for example—you need more iterations.
How m...
Pros and cons of Java rules engines [closed]
...2;
} else if (product.quantity >= 500 && product.quantity < 2000) {
product.discount = 5;
} else if (product.quantity >= 2000) {
product.discount = 10;
}
A rule engine replaces the above with
code that looks like this:
ruleEngine.applyRules(product);
Up to you to dec...
Does MySQL index foreign key columns automatically?
... index". I tried to drop it but I got the following error: "ERROR 1553 (HY000): Cannot drop index 'index_name': needed in a foreign key constraint". So, it's not possible to drop that index and keep the foreign key.
– Ciprian Stoica
Oct 20 '15 at 10:11
...
Get program execution time in the shell
... output format.
Example:
$ time sleep 2
real 0m2.009s
user 0m0.000s
sys 0m0.004s
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