MATH OPERATIONS

The Math Operations Dialog allows the user to perform basic math operations on the relation data.  It is opened by selecting the Math item from the Data menu.
The operations currently implemented are: Sum, Product, Count, Average, Standard-Deviation, Minimum and Maximum.  
All functions skip null values;  All functions operate on numeric (int or float) types only, except for the Count function.
To perform a specific operation simply select the function's button in the dialog.  The dialog will update to show the results.  The default function, which is viewed when the dialog is opened, is Sum.
The dialog displays all attribute names; next to each attribute name appears the result of the currently active function, applied to the values of this attribute's column. If the attribute type is not numeric, the string "NaN" is displayed instead.  In addition to that, a field labeled "Total" displays the result of the currently active function as applied to all numeric attributes of the relation.
You can instruct the math functions to apply only to selected tuples and/or key attributes; the dialog contains controls for turning on and off such behavior.

The Update button updates the Math Operations Dialog by recalculating all results.  It is useful if your relation has changed since the dialog was opened.  Note that you do not need to press this button after selecting a new function or the key-attributes/selected-tuples controls, because in these cases the dialog updates automatically.

The Close button, surprisingly, closes the Math Operations Dialog.


Note that xpg's math functions do not use Postgres queries for the calculations; xpg does the calculations by itself.  It makes things faster and less buggy ;)