Data Type Of The Result; Operands Of The Expression; Nulls; Float(54) And Double Precision Data - HP Neoview SQL Reference Manual

where vi is the i-th value of expression, wi is the i-th value of weight, and N is the cardinality
of the result table.

Data Type of the Result

The data type of the result is always DOUBLE PRECISION.

Operands of the Expression

The expression includes columns from the rows of the SELECT result table—but cannot include
an aggregate function. These expressions are valid:
VARIANCE (SALARY)
VARIANCE (SALARY * 1.1)
VARIANCE (PARTCOST * QTY_ORDERED)

Nulls

VARIANCE is evaluated after eliminating all nulls from the set. If the result table is empty,
VARIANCE returns NULL.

FLOAT(54) and DOUBLE PRECISION Data

Avoid using large FLOAT(54) or DOUBLE PRECISION values as arguments to VARIANCE. If
SUM(x * x) exceeds the value of 1.15792089237316192e77 during the computation of
VARIANCE(x), then a numeric overflow occurs.

Examples of VARIANCE

• Compute the variance of the salary of the current employees:
SELECT VARIANCE(salary) AS Variance_Salary
FROM persnl.employee;
VARIANCE_SALARY
-------------------------
1.27573263588496116E+009
--- 1 row(s) selected.
• Compute the variance of the cost of parts in the current inventory:
SELECT VARIANCE (price * qty_available)
FROM sales.parts;
(EXPR)
-------------------------
5.09652410092950336E+013
--- 1 row(s) selected.
VARIANCE Function 431