How to change custom fields in JIRA

Example illustrated below , how we change text custom fields to select custom fields in jira. 

1. Stop Jira
     $JBOSS_HOME/bin/shutdown -S

2. UPDATE customfield SET CUSTOMFIELDTYPEKEY='com.atlassian.jira.plugin.system.customfieldtypes:select', CUSTOMFIELDSEARCHERKEY=NULL where cfname="My Text Field";


3. Start Jira
  $JBOSS_HOME/bin/run.sh -b 0.0.0.0

4. Configure the custom field to add the options. I assume you have to add an option for every distinct value, which you can probably find with:


select * from customfieldvalue where customfield=(select id from customfield where cfname='My Text Field');

and then use some version of DISTINCT to identify the unique value. Text with spaces may cause a problem.
5. Edit the custom field to set the Searcher
6. Add options value in this fields if it is select fields.
6. Reindex



more details , please visit on this url :
http://confluence.atlassian.com/display/JIRA/Changing+Custom+Field+Types