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MOVINGVARIANCE Function
The MOVINGVARIANCE function is a sequence function that returns the variance of nonnull
values of a column in the current window of an intermediate result table ordered by a SEQUENCE
BY clause in a SELECT statement. See
MOVINGVARIANCE is a Neoview SQL extension.
MOVINGVARIANCE (column-expression,integer-expression
column-expression
specifies a derived column determined by the evaluation of the column expression.
integer-expression
is an SQL numeric value expression of signed data type SMALLINT or INTEGER that specifies
the current window. The current window is defined as the current row and the previous
(integer-expression - 1) rows.
max-rows
is an SQL numeric value expression of signed data type SMALLINT or INTEGER that specifies
the maximum number of rows in the current window.
Note these considerations for the window size:
•
The actual value for the window size is the minimum of integer-expression and
max-rows.
•
If these conditions are met, MOVINGVARIANCE returns the same result as
RUNNINGVARIANCE:
— The integer-expression is out of range, and max-rows is not specified. This
— The minimum of integer-expression and max-rows is out of range. In this
•
The number of rows is out of range if it is larger than the size of the result table, negative,
or NULL.
Example of MOVINGVARIANCE
Return the variance of nonnull values of a column in the current window of three rows:
SELECT MOVINGVARIANCE (I1,3) AS MOVINGVARIANCE3
FROM mining.seqfcn
SEQUENCE BY TS;
MOVINGVARIANCE3
-------------------------
0.00000000000000000E+000
2.41098840499999960E+008
2.19099696999999968E+008
2.28463602333333304E+008
3.64366210000000016E+007
--- 5 row(s) selected.
Note that you can use the CAST function for display purposes. For example:
SELECT CAST(MOVINGVARIANCE (I1,3) AS DEC (18,3))
FROM mining.seqfcn
SEQUENCE BY TS;
(EXPR)
--------------------
[,max-rows])
condition includes the case in which both integer-expression and max-rows
are larger than the result table.
case, integer-expression could be within range, but max-rows might be the
minimum value of the two and be out of range (for example, a negative number).
.000
"SEQUENCE BY Clause" (page
268).
MOVINGVARIANCE Function
375
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