Tutorial by Topics: ble

A data.table is an enhanced version of the data.frame class from base R. As such, its class() attribute is the vector "data.table" "data.frame" and functions that work on a data.frame will also work with a data.table. There are many ways to create, load or coerce to a data.tabl...

There are many excellent reference and example sources on the Web. Some examples and explanations are created here as a collection point for quick answers. More detailed illustrations may be linked to external content (instead of copying existing original material).

Partitioning is a functionality to split tables and indexes into smaller pieces. It is used to improve performance and to manage the smaller pieces individually. The partition key is a column or a set of columns that defines in which partition each row is going to be stored. Partitioning Overview ...

With 'Reproducibility' we mean that someone else (perhaps you in the future) can repeat the steps you performed and get the same result. See the Reproducible Research Task View. To create reproducible results, all sources of variation need to be fixed. For instance, if a (pseudo)random number ...

$global_variable @@class_variable @instance_variable local_variable Class variables are shared in the class hierarchy. This can result in surprising behavior. class A @@variable = :x def self.variable @@variable end end class B < A @@variable = :y end A.var...

DROP TABLE table_name; DROP TABLE IF EXISTS table_name; -- to avoid pesky error in automated script DROP TABLE t1, t2, t3; -- DROP multiple tables DROP TEMPORARY TABLE t; -- DROP a table from CREATE TEMPORARY TABLE ... ParametersDetailsTEMPORARYOptional. It specifies that only tempora...

ENV[variable_name] ENV.fetch(variable_name, default_value) Let get user profile path in a dynamic way for scripting under windows

Properties are observable and listeners can be added to them. They are consistently used for properties of Nodes.

AutoHotkey comes with many built-in functions and variables which can be used anywhere inside a script. For a full list including explanations, see: List of built-in variables List of built-in functions

An overview of Bash's internal variables, where, how, and when to use them.

Lack of an AUTO_INCREMENT id for this table -- The PK given is the 'natural' PK; there is no good reason for a surrogate. MEDIUMINT -- This is a reminder that all INTs should be made as small as is safe (smaller ⇒ faster). Of course the declaration here must match the definition in the tabl...