ODBC and JDBC Guide

Chapter 7
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Supported standards 39
ORDER BY clause
The ORDER BY clause indicates how the records are to be sorted. The format is:
ORDER BY {sort_expression [DESC | ASC]}, ...
sort_expression can be field names, expressions, or the positional number of the column expression to
use. The default is to perform an ascending (ASC) sort.
For example, to sort by last_name then by first_name, you could use either of the following SELECT
statements:
SELECT emp_id, last_name, first_name FROM emp ORDER BY last_name, first_name
or
SELECT emp_id, last_name, first_name FROM emp ORDER BY 2,3
In the second example, last_name is the second column expression following SELECT, so ORDER BY 2
sorts by
last_name.
FOR UPDATE clause
The FOR UPDATE clause locks records for Positioned Updates or Positioned Deletes via SQL cursors. The
format is:
FOR UPDATE [OF column_expressions]
column_expressions is a list of field names in the database table that you intend to update, separated by
a comma.
column_expressions is optional, and is ignored.
The following example returns all records in the employee database that have a SALARY field value of more
than $20,000. When each record is fetched, it is locked. If the record is updated or deleted, the lock is held
until you commit the change. Otherwise, the lock is released when you fetch the next record.
SELECT * FROM emp WHERE salary > 20000
FOR UPDATE OF last_name, first_name, salary