'Executes a DELETE query on the named table, expecting to delete a
single row.
Args:
table : string giving the table name
keyvalues : dict of column names and values to select the row with'

@staticmethod
def _simple_delete_one_txn(txn, table, keyvalues):

    sql = ('DELETE    FROM    %s    WHERE    %s' % (table, '    AND    '.join((('%s    =    ?' % (k,)) for k in keyvalues))))
    txn.execute(sql, keyvalues.values())
    if (txn.rowcount == 0):
        raise StoreError(404, 'No    row    found')
    if (txn.rowcount > 1):
        raise StoreError(500, 'more    than    one    row    matched')
