Making Queries Case Insensitive

With several third-party databases, it is common for queries to be case insensitive. For example, in such cases the following queries return the same results:

SELECT * FROM orders WHERE sales_rep = 'Oracle';
SELECT * FROM orders WHERE sales_rep = 'oracle';
SELECT * FROM orders WHERE sales_rep = 'OrAcLe';

If you want queries to be case insensitive for a user in the Oracle database, you can create an AFTER LOGON ON DATABASE trigger, in which you set, for that database user, the NLS_SORT session parameter to an Oracle sort name with _CI (for "case insensitive") appended.

The following example causes queries for user SMITH to use the German sort order and to be case insensitive:

CREATE OR REPLACE TRIGGER set_sort_order AFTER LOGON ON DATABASE
 DECLARE
  username VARCHAR2(30);
 BEGIN
  username:=SYS_CONTEXT('USERENV','SESSION_USER');
  IF username LIKE 'SMITH' then
   execute immediate 'alter session set NLS_COMP=LINGUISTIC';
   execute immediate  'alter session set NLS_SORT=GERMAN_CI';
  END IF;
 END;