• About Dangerous DBA
  • Table of Contents
Dangerous DBA A blog for those DBA's who live on the edge

DB2 RAND()

February 23, 2012 1:52 pm / Leave a Comment / dangerousDBA

Not done this for a while with moving house and looks like it will still be difficult with BT messing up the telephone lines in the building, but O2 are providing no end of support.  So thought I would do a short post in my lunch hour at work (actually taking a “break” for once) and do a short post.

One of the MySQL DBA colleagues asked me the other day if I could do a random update on a table, apart from the fact I could not understand at the time why you would want to randomly update a number of rows and not have an idea what you have done till you interrogate the data again, that’s another article for the what if I am allowed to publish it (doesn’t that sound intriguing!). The main IBM page in the DB2 Information Centre is here on the RAND() OLAP function.

So what’s the best way to update say 1000 rows in a 10000 row table randomly in DB2, I am not going to cover the way to do it on MySQL but heres how you could do it:

UPDATE <SCHEMA>.<TABLE> ST
SET <COLUMN> = SOMEVALUE
WHERE ST.<IDENTIFIER COLUM> = (SELECT <IDENTIFIER COLUM>
                              FROM <SCHEMA>.<TABLE>
                              ORDER BY RAND()
                              FETCH FIRST 1000 ROWS ONLY)

This code will randomly update 1000 rows, and will choose a different 1000 each time. You could but RAND() to other uses to create a random number but you will need to remember that it only generates a number between 1 and 0

So that’s it, one of my shorter ones.

Posted in: DB2, DB2 Administration, DB2 Built in commands, DB2 built in functions, DB2 Ecosystem, DB2 Maintenance, IBM, RAND, Uncategorized / Tagged: colum, information centre, olap, random number

Leave a Reply Cancel reply

Post Navigation

← Previous Post
Next Post →

Subscribe to Blog via Email

Enter your email address to subscribe to this blog and receive notifications of new posts by email.

Join 757 other subscribers

Recent Posts

  • Self generating Simple SQL procedures – MySQL
  • Google Cloud Management – My Idea – My White Whale?
  • Position Tracker – The Stub – Pandas:
  • Position Tracker – The Stub
  • Position Tracker – In the beginning
  • Whats been going on in the world of the Dangerous DBA:
  • QCon London Day 1
  • Testing Amazon Redshift: Distribution keys and styles
  • Back to dangerous blogging
  • DB2 10.1 LUW Certification 611 notes 1 : Physical Design

Dangerous Topics

added functionality ADMIN_EST_INLINE_LENGTH Bootcamp colum convert data types DB2 db2 DB2 Administration DB2 Development db2advis db2licm Decompose XML EXPORT GCP Google IBM IBM DB2 LUW idug information centre infosphere IOT LOAD merry christmas and a happy new year Position Tracking python Recursive Query Recursive SQL Reorganisation Reorganise Reorganise Indexes Reorganise Tables Runstats sql statement Stored Procedures SYSPROC.ADMIN_CMD Time UDF User Defined Functions V9.7 V10.1 Varchar XML XML PATH XMLTABLE

DangerousDBA Links

  • DB2 for WebSphere Commerce
  • My Personal Blog

Disclaimer:

The posts here represent my personal views and not those of my employer. Any technical advice or instructions are based on my own personal knowledge and experience, and should only be followed by an expert after a careful analysis. Please test any actions before performing them in a critical or nonrecoverable environment. Any actions taken based on my experiences should be done with extreme caution. I am not responsible for any adverse results. DB2 is a trademark of IBM. I am not an employee or representative of IBM.

Advertising

© Copyright 2022 - Dangerous DBA
Infinity Theme by DesignCoral / WordPress