SQL defines a set of status parameters that can be part of the
    parameter list for a procedure definition in a nonstored module.
    They are SQLSTATE, SQLCODE, and SQLCA. An SQL procedure is
    required to contain at least one of these status parameters in
    its parameter list. All status parameters are implicitly output
    parameters.

    The purpose of these status parameters is to return the status of
    each SQL statement that is executed. Each status parameter gives
    information that allows you to determine whether the statement
    completed execution or an exception has occurred. These status
    parameters differ in the amount of diagnostic information they
    supply, when an exception occurs as follows:

    o  SQLCODE-This is the original SQL error handling mechanism.
       It is an integer value. SQLCODE differentiates among errors
       (negative numbers), warnings (positive numbers), successful
       completion (0), and a special code of 100, which means no
       data. SQLCODE is a deprecated feature of the ANSI/ISO SQL
       standard.

    o  SQLCA-This is an extension of the SQLCODE error handling
       mechanism. It contains other context information that
       supplements the SQLCODE value. SQLCA is not part of the
       ANSI/ISO SQL standard. However, many databases such as DB2
       and ORACLE RDBMS have defined proprietary semantics and syntax
       to implement it.

    o  SQLSTATE-This is the error handling mechanism for the ANSI/ISO
       SQL standard. The SQLSTATE value is a character string that is
       associated with diagnostic information.

    See the Oracle Rdb SQL Reference Manual for more detailed
    information.