Editing the Persistent Properties of an Enterprise Bean 

Procedure

       1.      Choose a container-managed entity bean.

       2.      Choose the Persistent tab.

       3.      In the Table Name field, enter the name of the database table where the information from the CMP fields will be stored.

       4.      If the enterprise bean uses the database table only to read from it, select the Read Onlycheckbox.

This field is not mandatory, but you can obtain better performance results if you use it.

       5.      Choose the Field Mapping subtab. It contains table with information that describes the database mappings between CMP fields and columns in the database. Each row in this table describes one CMP field. The columns of the table have the following meanings:

¡        Field Name – the names of persistent fields for the container managed entity bean. This column lists the CMP fields you chose when Editing the Storage Properties of an Enterprise Bean.

¡        Field Type – the type of CMP field. It could be a dependent or non-dependent value class and is specified when the EJB JAR is created. How to manage dependent and non-dependent values is described below.

¡        Column Name –a column name for storing the value of the persistent property. It concerns managing the dependent and non-dependent value classes.

¡        Stored as byte array – this concerns managing the dependent value classes.

¡        Dependent Value Mapping – this concerns managing the dependent value classes.

       6.      Choose the Finder Descriptor tab. Its functionality is described in the Setting the Finder Methods section of Editing the Storage Properties of an Enterprise Bean.

       7.      Save your entries.

Managing Dependent and Non-Dependent Value Classes

The value of the Field Type column can be a dependent or a non-dependent value class.

Mapping Dependent Value Classes

If it is a dependent value class and:

·        all its fields are public - you can:

¡        Map each field of the dependent value class to a separate column in the database. To do this, click in the Dependent Value Mapping column. In the dialog box that appears in the column:

§         Field Name - lists all fields of the dependent value class.

§         Field Type – displays the type of each field.

§         Column Name – specify the name of the column that will store the value of the public field.

You should leave the Column Name column on the Field Mapping tab empty.

¡        Map all fields to one column, by:

...

                                                  i.       Checking the Store as byte array column.

                                                ii.       Setting a name for that column in the Column name column in the Field Mapping tab.

·        At least one field is not public - you can only map the properties to one column. In this case, the Store as byte array column is checked by default and the Default Value Mappingcolumn is not active. The default value of the Column Name column is <Field Name column value>_0, although you can change it.

Mapping Non-dependent Value Classes

If it is a non-dependent value class then you can map that CMP field to one column only in the database. In this case, the Store as byte array option and the Dependent Value Mapping columns are not active. You can only specify a name for that column in the Column Namefield.