April 15, 2011, 7:59 p.m.
posted by donnie
PivotTables: A Hack in Themselves
PivotTables are one of the wildest but most powerful features of Excel, an ingenious hack themselves that may take some experimentation to figure out.
We use PivotTables a lot when we develop spreadsheets for our clients. Once a client sees a PivotTable, they nearly always ask whether they can create one themselves. Although anyone can create a PivotTable, unfortunately many people tend to shy away from them, as they see them as too complex. Indeed, when you first use a PivotTable, the process can seem a bit daunting. Some persistence is definitely necessary.
You'll find that persistence will pay off once you experience the best feature of PivotTables: their ability to be manipulated using trial and error and immediately show the result of this manipulation. If the result is not what you expect, you can use Excel's Undo feature and have another go! Whatever you do, you are not changing the structure of your original table in any way, so you can do no harm.
Why Are They Called PivotTables?
PivotTables allow you to pivot data using drag-and-drop techniques and receive results immediately. PivotTables are interactive; once the table is complete, you very easily can see how your information will be affected when you move (or pivot) your data. This will become patently clear once you give PivotTables a try.
Even for experienced PivotTable developers, an element of trial and error is always involved in producing desired results. You will find yourself pivoting your table a lot!
What Are PivotTables Good For?
PivotTables can produce summary information from a table of information. Imagine you have a table of data that contains names, addresses, ages, occupations, phone numbers, and Zip Codes. With a PivotTable, you very easily and quickly can find out:
How many people have the same name
How many people share the same Zip Code
How many people have the same occupation
You also can receive such information as:
A list of people with the same occupation
A list of addresses with the same Zip Code
If your data needs slicing, dicing, and reporting, PivotTables will be a critical part of your toolkit.
Why Use PivotTables When Spreadsheets Already Offer So Much Analysis Capability?
Perhaps the biggest advantage to using PivotTables is the fact that you can generate and extract meaningful information from a large table of data within a matter of minutes and without using up a lot of computer memory. In many cases, you could get the same results from a table of data by using Excel's built-in functions, but that would take more time and use far more memory.
Another advantage to using PivotTables is that if you want some new information, you can simply drag-and-drop (pivot). In addition, you can opt to have your information update each time you open the workbook or click Refresh.
PivotCharts Extend PivotTables
Microsoft introduced PivotCharts in Excel 2000. The table you create via the PivotTable Wizard produces a PivotChart (or, more accurately, a PivotTable and PivotChart Report). When you create a PivotTable, you also can create a PivotChart at the same time, with no extra effort. PivotCharts enable you to create interactive charts that previously were impossible without using either VBA or Excel Controls.
Creating Tables and Lists for Use in PivotTables
When you create a PivotTable, you must organize the dataset you're using in a table and/or a list. As the PivotTable will base all its data on this table or list, it is vital that you set up your tables and lists in a uniform way.
In this context, a table is no more than a list that has a title, has more than one column of data, and has a different heading for each column. A list often is referred to in the context of a table as well. The best practices that apply to setting up a list will help you greatly when you need to apply a PivotTable to your data.
When you extract data via the use of lookup or database functions, you can be a little less stringent in how you set up the table or list. This is because you can always compensate with the aid of a function and probably still get your result. Nonetheless, it's still easiest to set up the list or table as neatly as possible. Excel's built-in features assume a lot about the layout and setup up of your data. Although they offer a degree of flexibility, more often than not you will find it easier to adhere to the following guidelines when setting up your table or list:
Headings are required, as a PivotTable uses them for field names. Headings should always appear in the row directly above the data. Also, never leave a blank row between the data and the headings. Furthermore, make the headings distinct in some way; for instance, boldface them.
If you have more than one list or table on the same worksheet, leave at least one blank column between each list or table. This will help Excel recognize them as separate entities. However, if the lists and tables are related to each other, combine them into one large table.
If you follow these guidelines as closely as possible, using PivotTables will be a relatively easy task.
Figure shows a well-laid out table of data, and a PivotTable in progress. Note that many of the same dates are repeated in the Date column. In front of this data is the Layout step for the data showing the optional Page, Row, and Column fields, as well as the mandatory Data field.
The PivotTable and PivotChart Wizard
As noted earlier, to help users create PivotTables, Excel offers a PivotTable and PivotChart Wizard. This Wizard guides you through the creation of a PivotTable using a four-step process, in which you tell Excel the following:
How the data is set up and whether to create an associated PivotChart (if PivotCharts are available in that version of Excel)
Where the data is stored—e.g., a range in the same workbook, a database, another workbook, etc.
Which column of data is going into which field: the optional Page, Row, and Column fields, as well as the mandatory Data field
Where to put your PivotTable (i.e., in a new worksheet or in an existing one)