JPA或Hibernate - 在不同类型的列上连接表

Question

Is there a way to tell Hibernate to wrap a column in a to_char when using it to join to another table or conversely convert a NUMBER to a VARCHAR? I have a situation where I have a table which contains a generic key column of type VARCHAR which stores the Id of another table which is a Number. I am getting a SQL exception when Hibernate executes the SQL it generates which uses '=' to compare the two columns.

Thanks...

PS I know this is not ideal but I am stuck with the schema so I have to deal with it.

Answer 1

This should be possible using a formula in your many-to-one. From section 5.1.22. Column and formula elements (solution also mentioned in this previous answer ):

column and formula attributes can even be combined within the same property or association mapping to express, for example, exotic join conditions.

 <many-to-one name="homeAddress" class="Address" insert="false" update="false"> <column name="person_id" not-null="true" length="10"/> <formula>'MAILING'</formula> </many-to-one> 

With annotations (if you are using Hibernate 3.5.0-Beta-2+, see HHH-4382 ):

@ManyToOne
@Formula(value="( select v_pipe_offerprice.offerprice_fk from v_pipe_offerprice where v_pipe_offerprice.id = id )")
public OfferPrice getOfferPrice() { return offerPrice; } 

Or maybe check the @JoinColumnsOrFormula :

@ManyToOne
@JoinColumnsOrFormulas(
{ @JoinColumnOrFormula(formula=@JoinFormula(value="SUBSTR(product_idnf, 1, 3)", referencedColumnName="product_idnf")) })
@Fetch(FetchMode.JOIN)
private Product productFamily;