Hibernate - <property> values vs. <column> values

Question

I'm back here in Stackoverflow wondering what the difference is between values in and within a Hibernate's hbm.xml file.

I explain myself a little better:

<property column="LOGIN_NAME" generated="insert" lazy="false" name="loginName" not-null="true" type="java.lang.String" unique="true">
    <column length="128" name="LOGIN_NAME" not-null="true" sql-type="VARCHAR(128)" unique="true"/>
</property>

In the above example I repeat some values such as not-null, unique or column-name in both <property> and <column>. My question(s) is, what's the difference? Which of those must/should be defined?

Answer 1

There is no requirement to have both the tags for the same representation. Instead of writing the way you have written above following is the way to write it.

<property column="LOGIN_NAME" generated="insert" lazy="false" name="loginName" not-null="true" type="java.lang.String" unique="true" sql-type="VARCHAR(128)" length="128">
</property>

The column tag is part of the property tag itself. You only need to define it once. Its not required to add same properties again and again.