Window name clause

Defines a named window that specifies window partition and order clauses for an analytic function. This window is specified in the function's OVER clause. Named windows can be useful when you write queries that invoke multiple analytic functions with similar OVER clauses—for example, they use the same partition (PARTITION BY) clauses.

Syntax

WINDOW window-name AS ( window-partition-clause [window-order-clause] )

Parameters

WINDOW window-name

Specifies the window name. All window names must be unique within the same query.

window-partition-clause `[` window-order-clause`]` : Clauses to invoke when an `OVER` clause references this window.

If the window definition omits a window order clause, the OVER clause can specify its own order clause. **

Requirements

• A WINDOW clause cannot include a window frame clause.

• Each WINDOW clause within the same query must have a unique name.

• A WINDOW clause can reference another window that is already named. For example, the following query names window w1 before w2. Thus, the WINDOW clause that defines w2 can reference w1:

  => SELECT RANK() OVER(w1 ORDER BY sal DESC), RANK() OVER w2
     FROM EMP WINDOW w1 AS (PARTITION BY deptno), w2 AS (w1 ORDER BY sal);
  

Examples

See Named windows.

See also

Analytic functions