大约有 48,000 项符合查询结果（耗时：0.0673秒） [XML]
A beginner's guide to SQL database design [closed]
...fmann Series in Data Management Systems) (Paperback) by Jan L. Harrington and found it very clear and helpful
and as you get up to speed this one was good too Database Systems: A Practical Approach to Design, Implementation and Management (International Computer Science Series) (Paperback)
I thin...
Java inner class and static nested class
What is the main difference between an inner class and a static nested class in Java? Does design / implementation play a role in choosing one of these?
...
Simulate CREATE DATABASE IF NOT EXISTS for PostgreSQL?
...r connection; role, port, password, ... See:
Run batch file with psql command without password
The same cannot be called with psql -c "SELECT ...\gexec" since \gexec is a psql meta‑command and the -c option expects a single command for which the manual states:
command must be either a command s...
Hibernate openSession() vs getCurrentSession()
...
As explained in this forum post, 1 and 2 are related. If you set hibernate.current_session_context_class to thread and then implement something like a servlet filter that opens the session - then you can access that session anywhere else by using the SessionFa...
What is difference between instantiating an object using new vs. without
...lock of memory by calling either ::operator new() or Time::operator new(), and subsequently calls Time::Time() with this set to an address within that memory block (and also returned as the result of new), which is then stored in t. As you know, this is generally done on the heap (by default) and re...
Why doesn't a python dict.update() return the object?
...
Python's mostly implementing a pragmatically tinged flavor of command-query separation: mutators return None (with pragmatically induced exceptions such as pop;-) so they can't possibly be confused with accessors (and in the same vein, assignment is not an expression, the statement-expressi...
What is the difference between OpenID and SAML?
What is the difference between OpenID and SAML?
4 Answers
4
...
Height equal to dynamic width (CSS fluid layout) [duplicate]
...
All you need to do is include the jQuery script and css styles. Check full code at jsfiddle.net/n6DAu/24
– Hussein
Jul 28 '11 at 6:12
36
...
How can I check if a Perl array contains a particular value?
... can also add more (unique) params to the list:
$params{$newparam} = 1;
And later get a list of (unique) params back:
@badparams = keys %params;
share
|
improve this answer
|
...
Replace all 0 values to NA
...ays in ?'NULL',
NULL represents the null object in R
which is unique and, I guess, can be seen as the most uninformative and empty object.1 Then it becomes not so surprising that
data.frame(x = c(1, NULL, 2))
# x
# 1 1
# 2 2
That is, R does not reserve any space for this null object.2 Mea...