Missing Manual - Before() and After()

robert_mika · Mar 31, 2015 8:22:17 AM

Have you ever wondered how the examples from the Qlikview help may look like?

Please see below and enjoy responsibly...

Before () and After()

Description

Returns the value of expression evaluated with a pivot table's dimension values as they appear in the column before the current column within a row segment in the pivot table. This function returns NULL in all chart types except pivot tables.

On the first column of a row segment a NULL value will be returned, as there is no column before this one.

If the table is one-dimensional or if the expression is preceded by the total qualifier, the current row segment is always equal to the entire row.

If the pivot table has multiple horizontal dimensions, the current row segment will include only columns with the same values as the current column in all dimension rows except for the row showing the last horizontal dimension of the inter field sort order. The inter field sort order for horizontal dimensions in pivot tables is defined simply by the order of the dimensions from top to bottom.

Specifying an offset greater than 1 lets you move the evaluation of expression to columns further to the left of the current column. A negative offset number will actually make the before function equivalent to a after function with the corresponding positive offset number. Specifying an offset of 0 will evaluate the expression on the current column. Recursive calls will return NULL.

By specifying a third parameter n greater than 1, the function will return not one but a range of n values, one for each of n table columns counting to the left from the original cell. In this form, the function can be used as an argument to any of the special Chart Range Functions.

Returns value from preceding (Before)or following (After) column
Returns values only in Pivot Table otherwise NULL.
Works only with Horizontal dimension.
Equivalent to below() and above() for vertical Pivot Table dimensions.

Data Model:

(Copy and Pasted below code into Edit Script window and reload)

LOAD * inline

[

Product ,Category ,Sales

Salt ,White, 30

Salt, Brown ,40

Salt ,Red ,30

Sugar ,White ,10

Sugar ,Brown ,20

Sugar ,Red ,20

Wine ,White ,40

Wine ,Brown ,30

Wine ,Red ,10

]

Example 1:

Let's build a Pivot Tables with Product as dimension and expressions as below:

The left hand side shows an ordinary use of Sales the right hand side result from our new expression.

sum( Sales ) -----------> before(sum( Sales ) )

Salt value has been assigned to Sugar,

Sugar to Wine,

Salt is now NULL .(there is no column before this one)

sum( Sales ) -----------> after(sum( Sales ) )

Here we see the opposite result:

Sugar value has been assigned to Salt,

Wine to Sugar

and Wine is NULL (no column after this one)

Example 2

Specifying the second criteria as 2 we shifted all values by 2 columns right or left.

before( sum( Sales ), 2 )

after( sum( Sales ), 2 )

Example 3

before(total sum( Sales ) )

after(total sum( Sales ) )

When using with one dimension this expression returns values as if we have used ordinary before/after (Sum(Sales))

For more than one dimension the return value will be based on last column of the first(top) dimension and then appropriate columns for the second dimension.