Hi,

Simple question. I have a simple User table with three columns and everything works fine (my mapping file is included below):

- 'userid' an int which autoincrements
- 'username' a varchar[50]
- 'password' a varchar[50]

SIMPLE QUESTION: Everything works fine, except currently the username field is not unique. I like having the 'userid' field be a unique identifier for the entire record -- but what's the easiest way to enforce uniqueness on the username as well?

I know I could code it in Java -- do a lookup for any existing user with that name before proceedind with the create -- but I'm guessing Hibernate (or mySql?) provides an easy way to handle this.

Any help is greatly appreciated! Thanks!

boxlight

#
My mapping file:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>

<class name="com.me.model.User" table="user">

<id name="userid" column="userid" >
<generator class="increment"/>
</id>

<property name="username">
<column name="username" />
</property>

<property name="password">
<column name="password"/>
</property>

</class>

</hibernate-mapping>

You can do it in the mapping file like this

Thanks for the help -- modifying the XML it didn't seem to work, though. I can still create duplicates. :-(

Do I need to modify the mysql table as well?

Yes. How do you create your tables? If you use the property "hibernate.hbm2ddl.auto" in hibernate.cfg.xml, hibernate will create the tables with the right unique constraints.

Look at table 3.7 in the link below for information on the hibernate.hbm2ddl.auto property. You can set it to "create" to get hibernate create the tables for you.

http://www.hibernate.org/hib_docs/v3/re ... n-optional