Selecting columns
You can click each column you want to include from the table
representations in the Table Layout view. PowerBuilder highlights
selected columns and places them in the Selection List at the top of
the SQL Select painter.
To reorder the selected columns
-
Drag a column in the Selection List with the mouse. Release
the mouse button when the column is in the proper position in the
list.
To select all columns from a table
-
Move the pointer to the table name and select Select All
from the pop-up menu.
To include computed columns
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Click the Compute tab to make the Compute view available (or
select View>Compute if the Compute view is not currently
displayed).Each row in the Compute view is a place for entering an
expression that defines a computed column. -
Enter one of the following:
-
An expression for the computed column. For example:
salary/12 -
A function supported by your DBMS. For example, the
following is a SQL Anywhere function:1substr("employee"."emp_fname",1,2)
You can display the pop-up menu for any row in the Compute
view. Using the pop-up menu, you can select and paste the
following into the expression:-
Names of columns in the tables used in the DataWindow or
pipeline -
Any retrieval arguments you have specified
-
Functions supported by the DBMS
About these functions
The functions listed here are provided by your DBMS. They
are not PowerBuilder functions. This is so because you are now
defining a SELECT statement that will be sent to your DBMS for
processing. -
-
Press the Tab key to get to the next row to define another
computed column, or click another tab to make additional
specifications.PowerBuilder adds the computed columns to the list of
columns you have selected.
About computed columns and computed
fields
Computed columns you define in the SQL Select painter are added
to the SQL statement and used by the DBMS to retrieve the data. The
expression you define here follows your DBMS’s rules.
You can also choose to define computed fields, which are created
and processed dynamically by PowerBuilder after the data has been
retrieved from the DBMS. There are advantages to doing this. For
example, work is offloaded from the database server, and the computed
fields update dynamically as data changes in the DataWindow object.
(If you have many rows, however, this updating can result in slower
performance.) For more information, see Enhancing DataWindow Objects.