If you specify sa_validate() (no arguments), the database server validates all tables, materialized views, indexes, checksums,
and the database file.
If neither owner nor tbl_name are specified, all tables and materialized views in the database are validated. Also, the database itself is validated, including
checksum validation, and validation that the number of rows in the each table or materialized view matches the number of rows
in each associated index.
The values for tbl_name and owner_name are strings and must be enclosed in quotes.
The procedure returns a single column named Messages. Errors returned during validation appear in the column. If validation
succeeds without error, the column contains No error detected.
Validating a table or an entire database should be performed while no connections are making changes to the database; otherwise,
errors may be reported indicating some form of database corruption even though no corruption actually exists.