Normally, errors occur for data-change statements (such as
          INSERT or
          UPDATE) that would violate
          primary-key, unique-key, or foreign-key constraints. If you
          are using a transactional storage engine such as
          InnoDB, MySQL automatically rolls back the
          statement. If you are using a nontransactional storage engine,
          MySQL stops processing the statement at the row for which the
          error occurred and leaves any remaining rows unprocessed.
        
          MySQL supports an IGNORE keyword for
          INSERT,
          UPDATE, and so forth. If you
          use it, MySQL ignores primary-key or unique-key violations and
          continues processing with the next row. See the section for
          the statement that you are using (Section 15.2.7, “INSERT Statement”,
          Section 15.2.17, “UPDATE Statement”, and so forth).
        
          You can get information about the number of rows actually
          inserted or updated with the
          mysql_info() C API function.
          You can also use the SHOW
          WARNINGS statement. See
          mysql_info(), and
          Section 15.7.7.42, “SHOW WARNINGS Statement”.
        
          InnoDB and NDB tables
          support foreign keys. See
          Section 1.6.3.2, “FOREIGN KEY Constraints”.