Two types of crosstabs
There are two types of crosstabs:
-
Dynamic
-
Static
Dynamic crosstabs
With dynamic crosstabs, PowerBuilder builds all the columns and
rows in the crosstab dynamically when you run the crosstab. The number
of columns and rows in the crosstab match the data that exists at
runtime.
Using the preceding crosstab as an example, if a new printer was
added to the database after the crosstab was saved, there would be an
additional row in the crosstab when it is run. Similarly, if one of
the quarter’s results was deleted from the database after the crosstab
was saved, there would be one less column in the crosstab when it is
run.
By default, crosstabs you build are dynamic.
Static crosstabs
Static crosstabs are quite different from dynamic crosstabs.With
static crosstabs, PowerBuilder establishes the columns in the crosstab
based on the data in the database when you define the crosstab. (It
does this by retrieving data from the database when you initially
define the crosstab.) No matter what values are in the database when
you later run the crosstab, the crosstab always has the same columns
as when you defined it.
Using the preceding crosstab as an example, if there were four
quarters in the database when you defined and saved the crosstab,
there would always be four columns (Q1, Q2, Q3, and Q4) in the
crosstab at runtime, even if the number of columns changed in the
database.
Advantages of dynamic
crosstabs
Dynamic crosstabs are used more often than static crosstabs, for
the following reasons:
-
You can define dynamic crosstabs very quickly because no
database access is required at definition time. -
Dynamic crosstabs always use the current data to build the
columns and rows in the crosstab. Static crosstabs show a snapshot
of columns as they were when the crosstab was defined. -
Dynamic crosstabs are easy to modify: all properties for the
dynamically built columns are replicated at runtime automatically.
With static crosstabs, you must work with one column at a
time.