Erases records from a relation. Before using the ERASE statement,
    you must start a read/write transaction and establish a record
    stream using a context variable with a FOR statement or a START_
    STREAM statement. You cannot erase records from a view that was
    formed with a WITH, REDUCED, or CROSS clause of an RDO record
    selection expression. Also, you cannot erase records from a view
    that was formed with a UNION clause of an SQL select expression.

    Example:

    RDO> START_TRANSACTION READ_WRITE RESERVING
    cont>  COLLEGES FOR EXCLUSIVE WRITE
    RDO>     FOR C IN COLLEGES
    cont>      ERASE C
    cont>    END_FOR
    RDO> COMMIT

1  –  Format

  (B)0ERASE q> context-var qwqqqqqqq>qqqqqwq>
                        mq> on-error qj

1.1  –  context-var

    A temporary name specified in an RSE for name recognition. You
    must define the context variable in a START_STREAM statement or
    in a FOR loop. Request HELP on RSE for more information.

1.2  –  on-error

    The ON ERROR clause, which specifies a host language statement or
    Oracle Rdb data manipulation statement to be performed if an Oracle Rdb
    error occurs. Request HELP on ON_ERROR for more information.

2  –  More

    You need the Oracle Rdb READ and ERASE privileges to the relation
    and the Oracle Rdb ERASE privilege to the database to use the ERASE
    statement.

    You cannot erase records from a view that was formed with one of
    the following clauses:

    o  WITH clause of an RDO record selection expression

    o  REDUCED TO clause of an RDO record selection expression

    o  CROSS clause of an RDO record selection expression

    o  UNION clause of an SQL select expression

    Prior to Version 4.1, Oracle Rdb allowed you to erase rows from a
    table that was directly joined with other tables. Beginning with
    Version 4.1, Oracle Rdb returns an error message if you try to erase
    a row under these conditions. For example, Oracle Rdb will return
    the error, $RDMS-E-JOIN_CTX_UPD, relation EMPLOYEES is part of
    a join, cannot be updated, when you try to execute the following
    query:

    FOR E IN EMPLOYEES CROSS D IN DEGREES OVER EMPLOYEE_ID
        WITH D.DEGREE= 'MA'
        ERASE E
    END_FOR

    In the preceding query, if an employee has two MA degrees, the
    same employee row will be joined to two different degree rows.
    Therefore, Oracle Rdb will try to delete the same row twice. The
    previous update query can be reworded into an equivalent form to
    achieve the desired results as follows:

    FOR E IN EMPLOYEES WITH
       (ANY D IN DEGREES WITH D.EMPLOYEE_ID = E.EMPLOYEE_ID)
       ERASE E
    END_FOR

    The rows can now be erased because the EMPLOYEES table is no
    longer directly joined to the DEGREES table. The use of this
    query guarantees that an employee row will not be deleted more
    than once.

    Note that some examples in the Guide to Using RDO, RDBPRE, and
    RDML will no longer work with the update rules created in Oracle Rdb
    Version 4.1. To run these examples, rewrite them using the ANY
    subquery mentioned previously.

3  –  Examples

    Example 1

    Assume you wish to erase all the records in the COLLEGES
    relation:

    RDO> START_TRANSACTION READ_WRITE RESERVING
    cont>  COLLEGES FOR EXCLUSIVE WRITE
    RDO> FOR C IN COLLEGES ERASE C END-FOR
    RDO> PRINT COUNT OF C IN COLLEGES
     0
    RDO> COMMIT

    This statement uses the loop established by the FOR statement and
    erases all the records from the COLLEGES relation.