System Tables

Is it possible to accomplish any SQL statement manipulating the System
tables?

I was wondering about the possibility to substitute the unrecognized
SQL
statements (ALTER TABLE table COLUMN , for instance) through some
queries to the system tables.

Nelio

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Nelio Alves Pereira Filho
IFX Networks - www.ifx.com.br
+55 11 3365-5863
nelio@ifx.com.br