Order

For each table in your database you can specify in which order its records should be displayed. This chapter describes how you can specify an order and what consequences it has.

Empty order

By default each newly created table has an empty order. This means that if you enter a new record, the created record is inserted at the current position, that is, behind the current record of the table. If you change some fields of a record, the position of the record within the table leaves unchanged.

Order by attributes

Sometimes it is useful to have the records sorted by a certain attribute, e.g. by the `Name' attribute if the table has such one.

In MUIbase you can specify for each table a list of attributes by which its records should be sorted. All records are first sorted by the first attribute in this list. If two records are equal in an attribute then the next attribute in the list determines the order. For each attribute you can specify if the records should be sorted ascending or descending.

For determining the order of attributes the rules of the following table are used:

Type        Order relation  

Integer     NIL < MIN_INT < ... < -1 < 0 < 1 < ... < MAX_INT
Choice      (Choice values are treated as integers)            

Real        NIL < -HUGE_VAL < ... < -1.0 < 0.0 < 1.0 < ... < HUGE_VAL

String      NIL < "" < ... < "a" < "AA" < "b" < ...   
Memo        (String comparison is done case insensitive)

Date        NIL < 1.1.0000 < ... < 31.12.9999

Time        NIL < 00:00:00 < ... < 23:59:59

Bool        NIL < TRUE

Reference   NIL < any_record    
            (Records itself are not comparable for ordering)

If you have specified an order for a table then the records are automatically rearranged whenever you add a new record or change an order relevant field of a record.

Changing orders

To specify an order list for the current table select menu item `Table - Change order'. This will open a window containing

• the name of the table in the window title.
• a list of all attributes of the table that can be used in the order list. This list is placed in the left part of the window. If you double click a name then the name will be inserted into the order list at the current cursor position.
• the current list of attributes used for ordering. This list is placed in the right part of the window. The top item in this list is the first attribute of the order list. You can rearrange items by dragging them to other positions in the list. To add further attributes drag them from the attribute list to the order list. You can remove an attribute from the order list by dragging the item out of the order list and dropping it onto the attribute list. Each entry in the order list has an arrow symbol pointing up or down on the left side. You can toggle the state of the arrow by double-clicking it. If an arrow is pointing up then the sorting order for this attribute is done ascending, if it is pointing down, it is done descending.
• a `Clear' button to clear the order list.
• two buttons `Ok' and `Cancel' for leaving the window.

To enter a new order list, first press the `Clear' button. Then use drag & drop as described above to build up a new list of attributes. If you want to have an empty order then just don't add any attributes to the order list.

When you are done specifying the order list, press the `Ok' button. MUIbase will then reorder all records of the table. As this can need some time, a busy mouse pointer will appear.

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