Eclipse + JBoss 5 + EJB3 Development Guide (11)

Connection policy for Entity beans (joined strategy)

In the previous article, a table was logically partitioned into multiple tables using a single table strategy. However, this can result in an empty nest field, that is, a logical table consists of only a subset of the fields, while the values of many fields in the physical table are null. To solve this problem, the T_accounts table can be physically partitioned into multiple tables. To make a comparison with the T_accounts table, create a new t_myaccounts table, as shown in Figure 1.

Figure 1 T_myaccounts Table

As you can see from the structure of the t_myaccounts, the first three fields of the T_accounts table are included in the table, and the last two are logically divided into different tables, so you create two physical tables: T_checkingaccount and T_ SavingsAccount. The two tables are structured as follows:

Figure 2 T_checkingaccount Table

Figure 3 T_savingsaccount Table