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Hibernate supports three basic inheritance mapping strategies, and each strategies has different way of implementations. Below are the three inheritance mapping strategies supported by Hibernate.
Table per class hierarchy: Exactly one table is required, limitation columns declared by sub class cannot have not null constraints.
Syntax: <discriminator> column with <sub class="name" discrimination-value="value">
Example:
Using annotation
Using xml
Table per concrete class: Each table defines columns for all the properties of super class. Number of sub class is equals to number of tables required(two sub class required two tables).
Limitation: The identity generator strategy is not allowed. If property is mapped on the super class, then column name must be same on all sub class table.
Syntax: <union-subclass>
Example:
Using annotation
Using xml
Table per sub class: Foreign key is maintained between tables so superclass and subclass association is mapped with one to one association.
Limitation: Required tables is equals to number of classes including super class, caused one or more join operations to be performed to instantiate instance of sub class.
Syntax: <joined-subclass> with <key> column
Example:
Using annotation
Using xml
References:
Reference 1
Reference 2
Reference 3
Done :)
- table per class hierarchy
- table per concrete class
- table per sub class
Table per class hierarchy: Exactly one table is required, limitation columns declared by sub class cannot have not null constraints.
Syntax: <discriminator> column with <sub class="name" discrimination-value="value">
Example:
Using annotation
Using xml
Table per concrete class: Each table defines columns for all the properties of super class. Number of sub class is equals to number of tables required(two sub class required two tables).
Limitation: The identity generator strategy is not allowed. If property is mapped on the super class, then column name must be same on all sub class table.
Syntax: <union-subclass>
Example:
Using annotation
Using xml
Table per sub class: Foreign key is maintained between tables so superclass and subclass association is mapped with one to one association.
Limitation: Required tables is equals to number of classes including super class, caused one or more join operations to be performed to instantiate instance of sub class.
Syntax: <joined-subclass> with <key> column
Example:
Using annotation
Using xml
References:
Reference 1
Reference 2
Reference 3
Done :)
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