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Real life example, when to use OUTER / CROSS APPLY in SQL
...plus_one
FROM master..spt_values
CROSS APPLY (SELECT 2 * CAST(number AS BIGINT)) CA1(doubled_number)
CROSS APPLY (SELECT doubled_number + 1) CA2(doubled_number_plus_one)
4) Unpivoting more than one group of columns
Assumes 1NF violating table structure....
CREATE TABLE T
(
Id INT PR...
Check if a number is int or float
...
Use isinstance.
>>> x = 12
>>> isinstance(x, int)
True
>>> y = 12.0
>>> isinstance(y, float)
True
So:
>>> if isinstance(x, int):
print 'x is a int!'
x is a int!
_EDIT:_
As pointed out, in case of long integers, the above won't w...
What are “named tuples” in Python?
...u may just want to use a dictionary in this situation. Named tuples can be converted to dictionaries using pt1._asdict() which returns {'x': 1.0, 'y': 5.0} and can be operated upon with all the usual dictionary functions.
As already noted, you should check the documentation for more information f...
C++实现一款简单完整的聊天室服务器+客户端 - C/C++ - 清泛网 - 专注C/C++及内核技术
...息缓冲区，循环队列
char buf[MESSAGE_COUNT][MESSAGE_LENGTH];
int rear; //循环队列的队尾
int front; //循环队列的队首
public:
bool toStop;
//构造函数
MessageBuffer();
//析构函数
virtual ~MessageBuffer();
//将消息放入消息缓冲区...
Execution time of C program
...s, for example, gettimeofday is basically a wrapper for clock_gettime that converts nanoseconds to microseconds.
– Peter Cordes
Apr 5 '19 at 8:11
add a comment
...
Python recursive folder read
...tory may change during script execution, it's recommended to
# immediately convert program arguments to an absolute path. Then the variable root below will
# be an absolute path as well. Example:
# walk_dir = os.path.abspath(walk_dir)
print('walk_dir (absolute) = ' + os.path.abspath(walk_dir))
for ...
What does “fragment” mean in ANTLR?
... to an inline function: It makes the grammar more readable and easier to maintain.
A fragment will never be counted as a token, it only serves to simplify a grammar.
Consider:
NUMBER: DIGITS | OCTAL_DIGITS | HEX_DIGITS;
fragment DIGITS: '1'..'9' '0'..'9'*;
fragment OCTAL_DIGITS: '0' '0'..'7'+;
fr...
How to generate a range of numbers between two numbers?
...
an alternative solution is recursive CTE:
DECLARE @startnum INT=1000
DECLARE @endnum INT=1050
;
WITH gen AS (
SELECT @startnum AS num
UNION ALL
SELECT num+1 FROM gen WHERE num+1<=@endnum
)
SELECT * FROM gen
option (maxrecursion 10000)
...
How can I shuffle the lines of a text file on the Unix command line or in a shell script?
...f. On some systems at least (doesn't appear to be in POSIX).
As jleedev pointed out: sort -R might also be an option. On some systems at least; well, you get the picture. It has been pointed out that sort -R doesn't really shuffle but instead sort items according to their hash value.
[Editor's not...
Import error: No module name urllib2
...uest and urllib.error. The 2to3 tool will automatically adapt imports when converting your sources to Python 3.
So you should instead be saying
from urllib.request import urlopen
html = urlopen("http://www.google.com/").read()
print(html)
Your current, now-edited code sample is incorrect becaus...