Thursday 26 November 2009

Keeping it positive

I had a request that when the result of a particular expression was negative, then it should just display as zero (it was a measure of how far out of compliance the result was - a negative result meant that they were in compliance so zero was appropriate).

So I could do a simple:

if(myExpression > 0, myExpression, 0)

That is OK if the expression is simple, but if the expression is more complex then it becomes unwieldy and long and hence difficult to maintain.

A much more elegant way is to use RangeMax like this:

RangeMax(0, myExpression)

Very simple, if my expression dips into the negative then the max value in the range becomes 0. Exactly what I want to achieve and much easier to maintain.

Friday 20 November 2009

Lies, damned lies...and then there is statistics

I spotted this in a Microstrategy publication which showed the "TCO" for Microstrategy over other operators:

This is a fairly typical use of a flawed statistic to prove a point.

You see, if you have a 10 user QlikView system, you have 1 IT person looking after it - the same guy that is looking after Windows, Email, buying coffee, etc. The same guy can probably look after QlikView as the company grows. So that is a 1 IT person for 10. Push that out to 1000 users and it become a "statistic" of 100 IT people per 1000.

Given that, until recently, QlikView has been playing more in the SME sector, then these numbers are going to be more than less typical. Therefore it probably says something that the "statistic" is only 21.9/1000.

At the other end, of course Microstrategy are best because of only 4.9 IT people per 1000. There is no real qualatitive data behind this. Microstrategy play in the Enterprise sector where they will regularly sell large CAL deals as well as open ended deals - we have no idea how many, exactly, users there are.

Its probably good to know that while your 21.9 QlikView IT people are busy looking after the Email server and making the coffee, your 4.9 Microstrategy guys are busy doing Microstrategy and nothing else.

Using Alerts in QlikView

Alerts are quite easy to set up. With a few tricks, they can become quite powerful.

Let me start with a very simple data set:

Country, Sales
England, 400
Ireland, 300
Scotland, 200
Wales, 100

Now, I want to create an Alert when there are any countries that have Sales > 200.

To create an alert, I need to be able to create an expression that will return a true value. I could use a simple aggr expression like:

=Sum(Aggr(If(Sum(Sales)>1, 1), Country)) > 0

This will work. However, it means that we are going to be limited to what information we can include in the Alert message. We can include the number of Countries, but we couldn't, for example, say which ones they were.

A more powerful way is to combine Advanced Search, Bookmarks and Alerts.

If I create an Advanced Search against the Country field such as:


Then I save this search as a Bookmark. Now, I can create an Alert with this Bookmark used where the Alert is simply:

=Count(Distinct Country) > 0

And the Alert message could be something like:

='Number of countries exceeding 200 = ' & Count(Distinct Country) & chr(13) &
'Countries: ' & Concat(Country, ', ')

Of course, I can bring any other information into this message that is related to the countries that match the Bookmark.

Now, if I set-up the "Mail" options under User Preferences, I can have this document email an alert to someone.

If I turn on the alert to use "Batch Mode", this can happen on the server when the document is reloaded.

Sunday 8 November 2009

AND Mode in list boxes

By default, multiple selections in list boxes are "OR" mode. For most applications this is exactly what we need.

However, there are situations, such as that requested by Wolfgang Praschnig on QlikCommunity this week:

Wolfgang wants to be able to see customers who have bought one product AND bought another product. The default action of QlikView would be to show customers who had bought one product or the other.

To enable "AND mode" in a list box, there are a couple of rules that we need to follow:

1. The field in the list box must be contained in a table that has only 2 fields.

2. The other field in the table is the association (or ID) field. This field is only contained in this table.

3. The table must have been loaded with the "DISTINCT" keyword.

This can sometimes be tricky to achieve, so hopefully an example will help demonstrate.

Lets say that we have 3 tables:

OrderID, CustomerID, OrderDate

OrderID, LineNo, ProductID, Quantity, Price

ProductID, ProductName

What we want to do is connect the product name to the Orders table in a way that we can employ AND mode.

This means that we will need to create a table that has the OrderID (to associate to Orders) and a ProductName field (which we will call "ProductNameAND") that we can put in our List Box with AND mode on.

So, first we need to create a table with the OrderID and ProductID from the OrderDetails table:

OrderID, ProductID As PID

Note that I have aliased the ProductID field as PID - this is because I am going to drop it in a minute. Also note the DISTINCT keyword.

Now, bring in the Product name:

ProductID As PID, ProductName As ProductNameAND

Finally, drop the PID field so we are left with only the 2 fields as required.


Now, we can add the ProductNameAND field in a List Box and the AND mode will be available.

Interesting feature here. When you click on an item in an AND mode box, an "&" will appear to the left of it. Pressing CTRL and clicking on additional "possible" (in white) items will add further "&"s beside those items. However, if you click on an "excluded" item or you click and hold the mouse down for a second on "possible" items, it turns to a "!" instead - i.e. "NOT". This can be really powerful for queries.

SR2 released and looking good

Well SR2 for QlikView 9 was released last week.

So far, so good. Looks like all my reported bugs have been fixed.

My opinion is that this Service Release is really what SR1 should have been if it hadn't been rushed forward to get some of the bad bugs from the initial release fixed.

With all of the great things that are in v9, we can now get on with the business of implementing it freely without having to worry about bugs that just shouldn't have been there.

Hurry over to QlikCommunity - - to get your copy.