Hello and welcome to the forum,
It is nonsense to post a topic title of DB2 in the db2 part of the forum. . .
Also, we don't read documentation and re-type the info - that is for you to research.
This is the Table of Contents for the SQL Language Reference:http://publibz.boulder.ibm.com/cgi-bin/ ... 0/CONTENTS
If you find something in the manual that is not clear, post what you found and your doubt - someone will be able to clarify.