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Reverse / invert a dictionary mapping
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Fun Fact: Dictionaries will be ordered (by time of insertion) in Python 3.7 onwards.
– byxor
Jun 12 '18 at 20:18
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List vs tuple, when to use each? [duplicate]
... You would want to change the values (go with list), but at the same time order and position is meaningful and consistent (go with tuple?).
– Arlen
Aug 23 '11 at 15:13
52
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Optimal way to concatenate/aggregate strings
...LECT
ID,
Name,
ROW_NUMBER() OVER (PARTITION BY ID ORDER BY Name) AS NameNumber,
COUNT(*) OVER (PARTITION BY ID) AS NameCount
FROM dbo.SourceTable
),
Concatenated AS
(
SELECT
ID,
CAST(Name AS nvarchar) AS FullName,
Name,
Nam...
Limiting the number of records from mysqldump?
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As the default order is ASC which is rarely what you want in this situation, you need to have a proper database design to make DESC work out of the box. If all your tables have ONE primary key column with the same name (natural or surrogate...
Using parameters in batch files at Windows command line
...process parameters without requiring that they are presented in a specific order. For example, a script may recognize the flags -a and -b in any order. A good way to parse the command line in such cases is
:parse
IF "%~1"=="" GOTO endparse
IF "%~1"=="-a" REM do something
IF "%~1"=="-b" REM do somet...
How to evaluate a math expression given in string form?
...described wiki.The logic of this algoritm starting from rules of operation orders. 1. operator sign | variable evaluation | function call | parenthesis (sub-expressions); 2. exponentiation; 3. multiplication, division; 4. addition, subtraction;
– Vasile Bors
J...
Linq 多字段排序，二次排序 - 更多技术 - 清泛网 - 专注C/C++及内核技术
Linq 多字段排序，二次排序Linq：ordered = source.OrderByDescending( t => t.f1 ).ThenBy( t => t.f2 );类似SQL：select * from t1 order by f1 d...Linq：ordered = source.OrderByDescending( t => t.f1 ).ThenBy( t => t.f2 );
类似SQL：select * from t1 order by f1 desc ,f2 asc
这种写...
In which scenario do I use a particular STL container?
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You now have unordered_map and unordered_set (and their multi variants) which are not in the flow chart but are good picks when you don't care about order but need to find elements by key. Their lookup is usually O(1) instead of O(log n).
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What's the purpose of SQL keyword “AS”?
...ProductRetailPrice,
O.Quantity
FROM Products AS P
LEFT OUTER JOIN Orders AS O ON O.ProductID = P.ProductID
WHERE O.OrderID = 123456
Example 3
It's a good practice to use the AS keyword, and very recommended, but it is possible to perform the same query without one (and I do often).
SELE...
What are the Dangers of Method Swizzling in Objective-C?
...ode
Possible naming conflicts
Swizzling changes the method's arguments
The order of swizzles matters
Difficult to understand (looks recursive)
Difficult to debug
These points are all valid, and in addressing them we can improve both our understanding of method swizzling as well as the methodology ...