大约有 13,370 项符合查询结果（耗时：0.0211秒） [XML]
Laravel migration: unique key is too long, even if specified
...e that VARCHAR may have 1, 2 or 4 bytes for each length unit. Example: utf8_mb4 (4 bytes) -> 767 / 4 = 191. Otherwise utf8_general_ci for VARCHAR(X) with X < 85 ( 1 byte ) = O(85) , or utf8_general_ci for VARCHAR(X) with X >= 86 ( 2 bytes ) -> 767 / 2 = 383. Consider also other columns l...
Delete an element from a dictionary
... use an an already constructed dict without a single item as **kwargs, some_function(**{k:v for k,v in some_dict.items() if k not 'some_key'})
– Cole
Nov 19 '17 at 21:14
...
LEFT JOIN only first row
...
If you can assume that artist IDs increment over time, then the MIN(artist_id) will be the earliest.
So try something like this (untested...)
SELECT *
FROM feeds f
LEFT JOIN artists a ON a.artist_id = (
SELECT
MIN(fa.artist_id) a_id
FROM feeds_artists fa
WHERE fa.feed_id = ...
Prevent direct access to a php include file
...tly (mainly a print() vs return()) Here's some modified code:
if(count(get_included_files()) ==1) exit("Direct access not permitted.");
The file being accessed is always an included file, hence the == 1.
share
...
Expand a random range from 1–5 to 1–7
...Here is a Python implementation, with a test harness:
import random
rand5_calls = 0
def rand5():
global rand5_calls
rand5_calls += 1
return random.randint(0, 4)
def rand7_gen():
state = 0
pow5 = 1
pow7 = 7
while True:
if state / pow5 == (state + pow7) / pow5:
...
How to reset db in Django? I get a command 'reset' not found error
...owing this Django by Example tutotrial here: http://lightbird.net/dbe/todo_list.html
10 Answers
...
Getting the class name from a static method in Java
...ass<?>> myself = StackWalker.getInstance(StackWalker.Option.RETAIN_CLASS_REFERENCE) .walk(s -> s.map(StackWalker.StackFrame::getDeclaringClass) .findFirst());, but of course, that’s connected to the fact that it will be much more powerful.
– Holger
...
What are best practices for validating email addresses on iOS 2.0
... *) candidate {
NSString *emailRegex =
@"(?:[a-z0-9!#$%\\&'*+/=?\\^_`{|}~-]+(?:\\.[a-z0-9!#$%\\&'*+/=?\\^_`{|}"
@"~-]+)*|\"(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21\\x23-\\x5b\\x5d-\\"
@"x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])*\")@(?:(?:[a-z0-9](?:[a-"
@"z0-9-]*[a-z0-9])?\\.)+[a-z0-...
What does “SyntaxError: Missing parentheses in call to 'print'” mean in Python?
...lt;module>
TypeError: unsupported operand type(s) for >>: 'builtin_function_or_method' and '_io.TextIOWrapper'. Did you mean "print(<message>, file=<output_stream>)"?
Since this error is raised when the code runs, rather than when it is compiled, it doesn't have access to the ...
Django REST framework: non-model serializer
... but it should work :)
The CalcClass:
class CalcClass(object):
def __init__(self, *args, **kw):
# Initialize any variables you need from the input you get
pass
def do_work(self):
# Do some calculations here
# returns a tuple ((1,2,3, ), (4,5,6,))
...