| Usage / Programming with DIALOG | |
When a DISPLAY ARRAY or INPUT ARRAY block is combined with a TABLE container, the row sorting feature is available implicitly. Row sorting is also supported on TREE containers, but only with DISPLAY ARRAY dialogs.
To sort rows in a list, the end user must click on a column header of the table. Clicking on a table column header triggers a GUI event that instructs the runtime system to reorder the rows displayed in the list container.
In fact, the rows are only sorted from a visual point of view; the data rows in the program array (the model) are left untouched. Therefore, when rows are sorted, the visual position of the current row might be different from the current row index in the program array.
To sort rows, the runtime system uses the standard collation order of the system, following the current locale settings. As result, the rows might be ordered a bit differently than when using the database server to sort rows (with an ORDER BY clause of the SELECT statement), since database servers can define their own collation sequences to sort character data.
The sorting feature is disabled when using the paged mode of DISPLAY ARRAY, because not all result set rows are known by the runtime system in this mode.
When an application window is closed, the selected sort column and order is stored by the front-end in the user settings database of the system (for example, on Windows™ platforms it's the registry database). The sort will be automatically re-applied the next time the window is created. This way, the rows will appear sorted when the program restarts. The saved sort column and order is specific to each list container.
The built-in sort is enabled by default. To prevent sorting in a TABLE orTREE containers, defined the UNSORTABLECOLUNMS attribute at the list container level, or set the UNSORTABLE attribute at the column/field level. As rows can be created and modified during an INPUT ARRAY instruction, you may want to use the UNSORTABLECOLUMNS attribute for tables controlled by INPUT ARRAY.