You could have a look at procedure dbms_utility.get_hash_value() described in dbmsutil.sql This turns an input string into a number. Make sure your developer is aware that two items that hash to the same value do not necessarily hold the same original value. Regards Jonathan Lewis http://www.jlcomp.demon.co.uk/faq/ind_faq.html The Co-operative Oracle Users' FAQ http://www.jlcomp.demon.co.uk/seminar.html Public Appearances - schedule updated Dec 23rd 2004 ----- Original Message ----- From: "Marquez, Chris" <CMarquez@xxxxxxxx> To: <oracle-l@xxxxxxxxxxxxx> Sent: Saturday, January 22, 2005 11:03 PM Subject: dbms_HASH...or something like it?...comparing data... Need some help. Developer has a wide table...20 columns. He would like to add a 21st column to the table. Then he would like to (be able to) store the first=20 20 columns data in concatenated form in the 21st column. For example; col1, col2, col3 Joe,Smith,JoeSmith No problem PL/SQL program can handle this, BUT he would rather store the 20 concatenated columns in=20 a simpler, tighter form. He suggested "hashing" the=20 20 concatenated columns to (I guess) an Alphanumeric string? And given that this is possible, what would be the=20 best/required data type for the hashed data? Why you ask? Because he want to be able to compare rows=20 (against new data) simply and quickly without selecting and=20 concatenating all 20 originally columns. So he would store the hashed version of a row (data) on Insert. Then on Update using a function hash the update data and compare it to the already hashed value in the row. =20 Any help is appreciated? Any other solution is appreciated, BUT his program is limited and=20 can only S,I,U,D and call PROCEDURES or FUNCTIONS. Please reply directly to me as well as to the list. Thanks in advance, Chris Marquez Oracle DBA HEYMONitor(tm) - heymonitor.com "Oracle Monitoring & Alerting Solution" -- //www.freelists.org/webpage/oracle-l -- //www.freelists.org/webpage/oracle-l