COSH

COSH

Syntax cosh::=

COSH ( n )

Purpose

COSH returns the hyperbolic cosine of n.

Examples

The following example returns the hyperbolic cosine of zero:

SELECT COSH(0) "Hyperbolic cosine of 0" FROM DUAL;

Hyperbolic cosine of 0

----------------------

1

COUNT

Syntax count::=

ALL

expr

See Also: "Analytic Functions" on page 6-10 for information on syntax, semantics, and restrictions

Purpose

COUNT returns the number of rows in the query. You can use it as an aggregate or analytic function.

6-40 Oracle9i SQL Reference

COUNT

If you specify DISTINCT, then you can specify only the query_partition_ clause of the analytic_clause. The order_by_clause and windowing_ clause are not allowed.

If you specify expr, then COUNT returns the number of rows where expr is not null. You can count either all rows, or only distinct values of expr.

If you specify the asterisk (*), then this function returns all rows, including duplicates and nulls. COUNT never returns null.

See Also:

■"Aggregate Functions" on page 6-8

■"About SQL Expressions" on page 4-2 for information on valid forms of expr

Aggregate Examples

The following examples use COUNT as an aggregate function:

SELECT COUNT(*) "Total" FROM employees;

Total

----------

107

SELECT COUNT(*) "Allstars" FROM employees

WHERE commission_pct > 0;

Allstars

---------

35

SELECT COUNT(commission_pct) "Count" FROM employees;

Count

----------

35

SELECT COUNT(DISTINCT manager_id) "Managers" FROM employees;

Managers

----------

18

Functions 6-41

COVAR_POP

Analytic Example

The following example calculates, for each employee in the employees table, the moving count of employees earning salaries in the range $50 less than through $150 greater than the employee’s salary.

SELECT last_name, salary,

COUNT(*) OVER (ORDER BY salary RANGE BETWEEN 50 PRECEDING

.

.

COVAR_POP

Syntax covar_pop::=

OVER ( analytic_clause )

COVAR_POP ( expr1 , expr2 )

See Also: "Analytic Functions" on page 6-10 for information on syntax, semantics, and restrictions

Purpose

COVAR_POP returns the population covariance of a set of number pairs. You can use it as an aggregate or analytic function.

Both expr1 and expr2 are number expressions. Oracle applies the function to the set of (expr1, expr2) pairs after eliminating all pairs for which either expr1 or expr2 is null. Then Oracle makes the following computation:

(SUM(expr1 * expr2) - SUM(expr2) * SUM(expr1) / n) / n

6-42 Oracle9i SQL Reference

COVAR_POP

where n is the number of (expr1, expr2) pairs where neither expr1 nor expr2 is null.

The function returns a value of type NUMBER. If the function is applied to an empty set, then it returns null.

See Also:

■"Aggregate Functions" on page 6-8

■"About SQL Expressions" on page 4-2 for information on valid forms of expr

Aggregate Example

The following example calculates the population covariance for the sales revenue amount and the units sold for each year from the sample table sh.sales:

SELECT t.calendar_month_number,

COVAR_POP(s.amount_sold, s.quantity_sold) AS covar_pop, COVAR_SAMP(s.amount_sold, s.quantity_sold) AS covar_samp FROM sales s, times t

WHERE s.time_id = t.time_id AND t.calendar_year = 1998

GROUP BY t.calendar_month_number;

Analytic Example

The following example calculates cumulative sample covariance of the list price and minimum price of the products in the sample schema oe:

Functions 6-43