大约有 23,000 项符合查询结果（耗时：0.0387秒） [XML]
Convert Decimal to Double
...is a type which is native to the CPU (internal representation is stored in base 2), calculations made with Double perform better then Decimal (which is represented in base 10 internally).
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im...
select * vs select column
...erlying on-disk storage structure for everything (including table data) is based on defined I/O Pages (in SQL Server for e.g., each Page is 8 kilobytes). And every I/O read or write is by Page.. I.e., every write or read is a complete Page of data.
Because of this underlying structural constraint...
Purpose of #!/usr/bin/python3
...re out what program should be started to interpret the script.
A non Unix based OS will use its own rules for figuring out how to run the script. Windows for example will use the filename extension and the # will cause the first line to be treated as a comment.
If the path to the Python executable...
How does mockito when() invocation work?
...on what param.
I found this article very helpful:
Explanation how proxy based Mock Frameworks work (http://blog.rseiler.at/2014/06/explanation-how-proxy-based-mock.html).
The author implemented a demonstration Mocking framework, which I found a very good resource for people who want to figure ou...
JOIN queries vs multiple queries
...ral queries? (You run your main query, and then you run many other SELECTs based on the results from your main query)
14 An...
Conditionally ignoring tests in JUnit 4
... like this:
@Test
public void calculateTotalSalary() {
assumeThat(Database.connect(), is(notNull()));
//test code below.
}
Not to mention that it is much easier to capture and use the connection from the Database.connect() method this way.
...
What is the difference between a HashMap and a TreeMap? [duplicate]
...
To sum up:
HashMap: Lookup-array structure, based on hashCode(), equals() implementations, O(1) runtime complexity for inserting and searching, unsorted
TreeMap: Tree structure, based on compareTo() implementation, O(log(N)) runtime complexity for inserting and searchi...
Java - JPA - @Version annotation
...oesn't matter if application uses only JPA for inserting data into the database, as JPA vendor will enforce 0 for @version field at creation time. But almost always plain SQL statements are also in use (at least during unit and integration testing).
...
Heroku/devise - Missing host to link to! Please provide :host parameter or set default_url_options[:
...nes to config/environments/production.rb in your app.
.
ActionMailer::Base.smtp_settings = {
:address => 'smtp.sendgrid.net',
:port => '587',
:authentication => :plain,
:user_name => ENV['SENDGRID_USERNAME'],
:password => ENV['SENDG...
Difference between Convert.ToString() and .ToString()
...tring tries to use IFormattable and IConvertible interfaces before calling base Object.ToString.
Example:
class FormattableType : IFormattable
{
private double value = 0.42;
public string ToString(string format, IFormatProvider formatProvider)
{
if (formatProvider == null)
...