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VirtualBase is a "table-on-the-fly". It is a data structure that can be accessed via the usual database interface. A VirtualBase table does not exist on any database platform as such. Instead, it was created, used, and disposed of all in the single page run. Alternatively, you can save the VirtualBase into a file (the "unload" action) so that you can re-create it in the future (the "load" action).
VirtualBase is useful in keeping temporary data that require database-like access interface like sorting, filtering, column and row selective processing etc. Sometimes VirtualBase is used to hold design attributes for run-time input. For example, Site-map can be easily done with VirtualBase and the "dbtree" command.
There are only three VirtualBase specific actions. Once a VirtualBase table is instantiated, you can access it in the "query" mode or the "action" mode as if it is an ordinary database table.
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VirtualBase Actions |
Description |
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create |
Create a new VirtualBase. Table definition can be specified using "create" SQL statement. |
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load[:file] |
Parse a file for VirtualBase query, which is usually starting with a "create" statement followed by many "insert" statements. (Action "load" does a "create" implicitly before parsing the file.) The file argument is default to the name of dbobj. |
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unload[:file] |
Save the VirtualBase to a file in the form of VirtualBase query. The saved file is in the format that the "load" action can parse. The file argument is default to the name of dbobj. |
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showcreatetable |
Return the "create table" SQL statement via the dbobj%result variable (string). |
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showinsertinto |
Return the "insert into" SQL statements of all data rows via the dbobj%result variable (array, one element for each row). |
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