Count Window Function; Examples Of Count Window Function - HP Neoview SQL Reference Manual

COUNT Window Function

COUNT is a window function that returns the count of the non null values of the given expression
for the current window specified by the inline-window-specification.
COUNT {(*) | ([ALL] expression) } OVER
inline-window-specification
inline-window-specification is:
[PARTITION BY expression [, expression]...]
[ORDER BY expression [ASC[ENDING] | DESC[ENDING]]
[ window-frame-clause ]
window-frame-clause is:
ROW CURRENT ROW
| ROW preceding-row
| ROW BETWEEN preceding-row AND preceding-row
| ROW BETWEEN preceding-row AND CURRENT ROW
| ROW BETWEEN preceding-row AND following-row
| ROW BETWEEN CURRENT ROW AND CURRENT ROW
| ROW BETWEEN CURRENT ROW AND following-row
| ROW BETWEEN following-row AND following-row
preceding-row is:
UNBOUNDED PRECEDING
| unsigned-integer PRECEDING
following-row is:
UNBOUNDED FOLLOWING
| unsigned-integer FOLLOWING
ALL
specifies whether duplicate values are included in the computation of the COUNT of the
expression. The default option is ALL, which causes duplicate values to be included.
expression
specifies a value expression that is to be counted. See
inline-window-specification
specifies the window over which the COUNT is computed. The
inline-window-specification can contain an optional PARTITION BY clause, an
optional ORDER BY clause and an optional window frame clause. The PARTITION BY clause
specifies how the intermediate result is partitioned and the ORDER BY clause specifies how
the rows are ordered within each partition.
window-frame-clause
specifies the window within the partition over which the COUNT is computed.

Examples of COUNT Window Function

• Return the running count of the SALARY column:
SELECT empnum, COUNT(salary)
OVER (ORDER BY empnum ROWS UNBOUNDED PRECEDING)
FROM persnl.employee;
• Return the running count of the SALARY column within each department:
SELECT deptnum, empnum, COUNT(salary)
OVER (PARTITION BY deptnum ORDER BY empnum ROWS UNBOUNDED PRECEDING)
FROM persnl.employee;
• Return the moving count of salary within each department over a window of the last 4 rows:
[,expression [ASC[ENDING] | DESC[ENDING]]]...]
"Expressions" (page 255).
COUNT Window Function 495