Scripting - QlikView 11 for Developers - page 235

Conditional functions
Often in QlikView, you want to modify the data based on a condition. For example,
we may want to classify any aircraft that was present in the database before 1990
as "Classic", and classify everything from 1990 onward as "Current". Let's open the
script editor and see how this is done:

1. Locate the [Aircraft Types] LOAD statement.

2. Add a comma behind the line END_DATE as [Aircraft End Date] and

press Return to create a new line.

3. On the new line, put the following expression: If(Year(BEGIN_DATE) <

1990, 'Classic', 'Current') as [Aircraft Age Classification]

4. As the 2010 update only contains aircraft that are newer than 2010, we do not

need to use the conditional expression, instead we can use a fixed value.

5. Add a comma behind the line END_DATE as [Aircraft End Date] and

press Return to create a new line.

6. Put the following expression on this line: 'Current' as [Aircraft Age

Classification]

7. Save and reload the document.

8. Add Aircraft Age Classification field to the Aircraft multibox.

When we select the value Classic from the Aircraft Age Classification drop-down
list, we see that only dates before the year 1990 are being selected.

The expression uses the If function as follows:

If(Year(BEGIN_DATE) < 1990, 'Classic', 'Current') as [Aircraft Age
Classification]

The If function takes three parameters:

• A condition, in our case Year(BEGIN_DATE) < 1990 , which returns true if
the year of the date is before 1990. Otherwise false is returned
• The expression to use if the condition is true : 'Classic'
• The expression to use if the condition is false : 'Current'

As we will see later, QlikView has many other conditional functions. However,
the If function is the most common. For those who want to check the available
conditional functions, select Help | Help from the menu, choose the Index tab, and
search for Conditional functions .