Release 10.1A: OpenEdge Development:
Progress 4GL Handbook

Temp-table buffer methods and attributes

In addition to the default buffer handle that is an attribute of every temp-table, you can create one or more dynamic buffers for a dynamic temp-table. Use this syntax:

CREATE BUFFER buffer-handle FOR TABLE tt-handle:DEFAULT-BUFFER-HANDLE     [ BUFFER-NAME buffer-name ] [ IN WIDGET-POOL pool-name ].

Note that it is necessary to include the reference to the DEFAULT-BUFFER-HANDLE. For example, you can create a second dynamic buffer for the temp-table in the current example with these statements:

DEFINE VARIABLE hTT AS HANDLE     NO-UNDO. DEFINE VARIABLE hTTB AS HANDLE     NO-UNDO. CREATE TEMP-TABLE hTT. hTT:CREATE-LIKE("Customer","Name"). hTT:ADD-FIELDS-FROM("SalesRep","MonthQuota"). hTT:ADD-LIKE-FIELD("Area", "SalesRep.Region"). hTT:ADD-NEW-FIELD("Sequence", "INTEGER",0,"9999",1000). hTT:ADD-LIKE-INDEX("CustNum","CustNum","Customer"). hTT:ADD-NEW-INDEX("SeqIndex", YES). hTT:ADD-INDEX-FIELD("SeqIndex", "Sequence"). hTT:TEMP-TABLE-PREPARE("CustSequence"). CREATE BUFFER hTTB FOR TABLE hTT:DEFAULT-BUFFER-HANDLE     BUFFER-NAME "CustSeq2".

Now you have two dynamic buffers for the temp-table, one called CustSeq that you get “for free” along with the temp-table definition and a second that you created yourself.

The dynamic buffer methods that you learned about earlier are essential to using dynamic temp-tables and their buffer. In particular, you will use the BUFFER-CREATE method on the buffer handle to create records in the dynamic temp-table, BUFFER-DELETE to delete them, BUFFER-RELEASE to release them, and BUFFER-COPY to copy fields from one or more database tables into newly created records in the temp-table.

There are a couple of additional buffer methods and attributes specific to their association with temp-tables, however.

TABLE-HANDLE buffer attribute

This attribute returns the handle of the temp-table the buffer is associated with. For a buffer not associated with a temp-table, it returns the Unknown value (?). Therefore, the temp-table’s DEFAULT-BUFFER-HANDLE points to its default buffer, and that buffer’s TABLE-HANDLE attribute points back to the temp-table. In addition, the TABLE-HANDLE attribute of any other buffer defined or created for the temp-table, such as CustSeq2, also points back to the temp-table.

EMPTY-TEMP-TABLE buffer method

It is much more efficient to empty a temp-table in one statement rather than in a FOR EACH loop. To empty a static temp-table you can use the EMPTY TEMP-TABLE tt-name statement. With the handle of a buffer for the temp-table, you can also use the EMPTY-TEMP-TABLE method on the buffer. It takes no arguments. Remember that while you can have multiple buffers associated with a temp-table, just as you can with a database table, there is only one set of records in the temp-table. The multiple buffers simply allow you to have pointers to multiple different records in the temp-table at the same time. Thus, you can use the EMPTY-TEMP-TABLE method on any buffer for the temp-table and the result is the same.