ri > Arel::WindowPredications

Che Dong

📖 NAME

Arel::WindowPredications

📁 Also found in: /home/chedong/.local/share/rdoc

🚀 Quick Reference

Use Case	Command	Description
🧩 Define a window for a query	`over(window)`	Applies a window function to a column or expression
📦 Create a named window	`window(name)`	Defines a reusable window specification
🔀 Partition data within a window	`partition(expr)`	Groups rows by one or more columns
📊 Order rows within a partition	`order(expr)`	Specifies the ordering of rows in the window
📏 Define a frame (rows/range)	`rows(range)` / `range(range)`	Limits the window to a subset of rows relative to the current row

📄 DESCRIPTION

Arel::WindowPredications is a module in the Arel library that provides methods for building SQL window function clauses. Window functions perform calculations across a set of rows related to the current row, without collapsing them into a single output row. This module is mixed into Arel attribute nodes to enable fluent construction of OVER, PARTITION BY, ORDER BY, and frame specifications.

🔧 Included Methods

over(window = nil) – Creates a OVER clause with an optional window name or definition.
window(name) – Generates a WINDOW clause for named windows.
partition(*exprs) – Adds a PARTITION BY clause.
order(*exprs) – Adds an ORDER BY clause.
rows(range) – Defines a row-based frame (e.g., ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING).
range(range) – Defines a range-based frame.

📚 SEE ALSO

Arel::Nodes::Window – The underlying AST node for window definitions.
Arel::Window – Higher-level window builder.
MySQL Window Functions – SQL reference for window functions.

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