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Create an empty data.frame
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You could use read.table with an empty string for the input text as follows:
colClasses = c("Date", "character", "character")
col.names = c("Date", "File", "User")
df <- read.table(text = "",
colClasses = colClasses,
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How to declare an array in Python?
... while some extra space
insert operation is expensive
Check this awesome table of operations complexity.
Also, please see this picture, where I've tried to show most important differences between array, array of references and linked list:
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What is the difference between Scope_Identity(), Identity(), @@Identity, and Ident_Current()?
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The ident_current(name) returns the last identity created for a specific table or view in any session.
The identity() function is not used to get an identity, it's used to create an identity in a select...into query.
The session is the database connection. The scope is the current query or the c...
How do I represent a hextile/hex grid in memory?
...u/~amitp/game-programming/grids (the diagrams are for square grids but the table includes the formulas for axial hex grids also)
– amitp
Jun 7 '13 at 0:58
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INSERT INTO vs SELECT INTO
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They do different things. Use INSERT when the table exists. Use SELECT INTO when it does not.
Yes. INSERT with no table hints is normally logged. SELECT INTO is minimally logged assuming proper trace flags are set.
In my experience SELECT INTO is most commonly used ...
What is the fastest integer division supporting division by zero no matter what the result is?
...y accessible in C through using idiom. That is why it so hard to make a portable multiple precision integer library in C without resorting to (inline) assembly. My guess is that most decent compilers will understand the above idiom.
Another way of avoiding branches, as also remarked in some of the ...
SCOPE_IDENTITY() for GUIDs?
...ng OUTPUT. This works when you're inserting multiple records also.
CREATE TABLE dbo.GuidPk (
ColGuid uniqueidentifier NOT NULL DEFAULT NewSequentialID(),
Col2 int NOT NULL
)
GO
DECLARE @op TABLE (
ColGuid uniqueidentifier
)
INSERT INTO dbo.GuidPk (
Col2
)
OUTPUT in...
Possibility of duplicate Mongo ObjectId's being generated in two different collections?
...of different "types" in the same collection, so why not just put your two "tables" in the same collection. They would share the same _id space, and thus, would be guaranteed unique. Switching from "prospective" to "registered" would be a simple flipping of a field...
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MongoDB Many-to-Many Association
...y relationship)? Even the MongoDB docs hint that you should avoid having mutable, huge arrays of references. docs.mongodb.org/manual/tutorial/…
– CaptSaltyJack
Feb 1 '15 at 20:07
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Can I use multiple “with”?
... + '%', X.[SQL]) > 0
) AS INC
)
And yes, you can reference common table expression inside common table expression definition. Even recursively. Which leads to some very neat tricks.
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