The recordmismatch function is used to locate differences between two tables in an equal join. The joining columns must contain all of the columns of a unique index. When the recordmismatch function isused, records only appear in the query where mismatches occur. Therefore, if a database has ten thousand records and exactly two records are different, then the query returns two records in the results set.
Example:
SELECT a.*, b.*
FROM rms_db.dbo.tab a, oracle_db.dbo.tab b
WHERE
a.unique_key = b.unique_key
{recordmismatch} /* check for differences between the records*/