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(slib.info)Relational Database Operations

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Relational Database Operations
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These are the descriptions of the methods available from an open
relational database.  A method is retrieved from a database by calling
the database with the symbol name of the operation.  For example:

     (define my-database
             (create-alist-database "mydata.db"))
     (define telephone-table-desc
             ((my-database 'create-table) 'telephone-table-desc))

 - Function: close-database
     Causes the relational database to be written to its associated
     file (if any).  If the write is successful, subsequent operations
     to this database will signal an error.  If the operations completed
     successfully, `#t' is returned.  Otherwise, `#f' is returned.

 - Function: write-database filename
     Causes the relational database to be written to FILENAME.  If the
     write is successful, also causes the database to henceforth be
     associated with FILENAME.  Calling the `close-database' (and
     possibly other) method on this database will cause FILENAME to be
     written to.  If FILENAME is `#f' this database will be changed to
     a temporary, non-disk based database if such can be supported by
     the underlying base table implelentation.  If the operations
     completed successfully, `#t' is returned.  Otherwise, `#f' is
     returned.

 - Function: sync-database
     Causes any pending updates to the database file to be written out.
     If the operations completed successfully, `#t' is returned.
     Otherwise, `#f' is returned.

 - Function: table-exists? table-name
     Returns `#t' if TABLE-NAME exists in the system catalog, otherwise
     returns `#f'.

 - Function: open-table table-name mutable?
     Returns a "methods" procedure for an existing relational table in
     this database if it exists and can be opened in the mode indicated
     by MUTABLE?, otherwise returns `#f'.

These methods will be present only in databases which are MUTABLE?.

 - Function: delete-table table-name
     Removes and returns the TABLE-NAME row from the system catalog if
     the table or view associated with TABLE-NAME gets removed from the
     database, and `#f' otherwise.

 - Function: create-table table-desc-name
     Returns a methods procedure for a new (open) relational table for
     describing the columns of a new base table in this database,
     otherwise returns `#f'.  For the fields and layout of descriptor
     tables, Note: Catalog Representation.

 - Function: create-table table-name table-desc-name
     Returns a methods procedure for a new (open) relational table with
     columns as described by TABLE-DESC-NAME, otherwise returns `#f'.

 - Function: create-view ??
 - Function: project-table ??
 - Function: restrict-table ??
 - Function: cart-prod-tables ??
     Not yet implemented.