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data.table vs dplyr: can one do something well the other can't or does poorly?
...ese aspects to provide a comprehensive answer/comparison (in no particular order of importance): Speed, Memory usage, Syntax and Features.
My intent is to cover each one of these as clearly as possible from data.table perspective.
Note: unless explicitly mentioned otherwise, by referring to dpl...
Differences between MySQL and SQL Server [closed]
...ample, take a look at the top-n section. In MySQL:
SELECT age
FROM person
ORDER BY age ASC
LIMIT 1 OFFSET 2
In SQL Server (T-SQL):
SELECT TOP 3 WITH TIES *
FROM person
ORDER BY age ASC
share
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What is the difference between char, nchar, varchar, and nvarchar in SQL Server?
...low.
DECLARE @T TABLE
(
C1 VARCHAR(20) COLLATE Chinese_Traditional_Stroke_Order_100_CS_AS_KS_WS,
C2 NVARCHAR(20)COLLATE Chinese_Traditional_Stroke_Order_100_CS_AS_KS_WS
)
INSERT INTO @T
VALUES (N'中华人民共和国',N'中华人民共和国'),
(N'abc',N'abc');
SELECT C1,
...
Will the base class constructor be automatically called?
...The constructors for each type in the type hierarchy will be called in the order of Most Base -> Most Derived.
So in your particular instance, it calls Person(), and then Customer() in the constructor orders. The reason why you need to sometimes use the base constructor is when the constructors...
How do I get a raw, compiled SQL query from a SQLAlchemy expression?
...q = DBSession.query(model.Name).distinct(model.Name.value) \
.order_by(model.Name.value)
Or just any kind of session.query().
Thanks to Nicolas Cadou for the answer! I hope it helps others who come searching here.
...
What is the best way to solve an Objective-C namespace collision?
...
This is gross, but you could use distributed objects in order to keep one of the classes only in a subordinate programs address and RPC to it. That will get messy if you are passing a ton of stuff back and forth (and may not be possible if both class are directly manipulating view...
How to change Git log date formats
...ke:
git config --global alias.lg "log --graph --decorate
-30 --all --date-order --date=format:'%Y-%m-%d %H:%M:%S'
--pretty=format:'%C(cyan)%h%Creset %C(black bold)%ad%Creset%C(auto)%d %s'"
I haven't been able to find this in documentation anywhere (if someone knows where to find it, please comme...
What is an index in SQL?
...visited/scanned.
In SQL Server, a clustered index determines the physical order of data in a table. There can be only one clustered index per table (the clustered index IS the table). All other indexes on a table are termed non-clustered.
SQL Server Index Basics
SQL Server Indexes: The Basics
SQL...
How to check if a Constraint exists in Sql server?
... FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS where CONSTRAINT_NAME = 'UNIQUE_Order_ExternalReferenceId') BEGIN ALTER TABLE Order ADD CONSTRAINT UNIQUE_Order_ExternalReferenceId UNIQUE (ExternalReferenceId) END
– The Coder
Apr 15 '14 at 21:00
...
Good example of livelock?
...uld wait.
The proper fix is to always respect the lock heirarchy. Pick an order in which you acquire the locks and stick to that. For example if both threads always acquire lock1 before lock2, then there is no possibility of deadlock.
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