dynamic joincolumn and join clause with variables - sql

Question

I have a unidirectional one-to-one relation. what I want to achieve is either
create a join on clause using CASE and sending variables to it so that I can change the join column (any other suggestions to change join column are also welcomed)
ignore the first clause created by hibernate and create specific ON clause using criteria as in the bottom of the question.
My query that works in SQL Manager:
SELECT d.Description, d.AccountId, d.PartnerId, a.FormattedName FROM
InvoiceDesigns d
INNER JOIN UserAccount a
ON
a.id =
CASE
WHEN d.PartnerId != -1 AND d.AccountId = 1 THEN d.PartnerId
WHEN d.PartnerId = 1 THEN d.AccountId
ELSE 1
END
WHERE
d.AccountId = 1 OR PartnerId = 1
The working query runs in SQL Manager, not in hibernate. it is the thing I want to achieve, I want hibernate to create a query like this.
When an account, lets say ID = 1 to stick with example, displays designs they will see
A) PartnerId of design is NOT -1 AND AccountId is 1, which means it is created by a partner for that account and will display partner's formattedName.
This is for normal accounts when viewing their avaiable designs. If a partner created a design for them, they will see that partner's name.
B) PartnerId equals to ID of the account, which means it is a Partner design and formattedName of the account related design is created for will be displayed.
This is for partner accounts to view designs they created.
C) Design is created by the account directly, so will display its own name. For normal accounts and self created designs.
Normal join is working fine in hibernate when I want to use only the AccountId or PartnerId but I need to change the column to get the related FormattedName. I tried #Where, #Filter, #JoinColumnOrFormula but I wasn't able to achieve this query.
My classes with #Where basically look like this:
Design class:
#Id #GeneratedValue(strategy=GenerationType.IDENTITY)
#Column(name="id")
int id;
#Column(name="AccountId")
int accountId;
#Column(name="PartnerId")
int partnerId;
#OneToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "AccountId", referencedColumnName = "id", insertable = false, updatable = false, nullable = true)
#Where(clause = "CASE " +
"WHEN PartnerId != -1 AND AccountId = :accountId THEN PartnerId " +
"WHEN PartnerId = :accountId THEN AccountId " +
"ELSE :accountId " +
"END")
AccountData account;
Account class:
#Id #GeneratedValue(strategy=GenerationType.IDENTITY)
#Column(name="id")
int id;
#Column(name="FormattedName")
String formattedName;
Here you can see that I want to send an ID to query as parameter using ":accountId" which will be used to define the join column.
this question: custom join clause actually does something similar. That is why I focused on where clause
Addition: I also found something with criteria
Criteria criteria = session.createCriteria(InvoiceDesignData.class, "design");
criteria.createCriteria("design.account", "acc", JoinType.LEFT_OUTER_JOIN, Restrictions.eqProperty("acc.id", "design.partnerId"));
invoiceDesignList = criteria.list();
But this does not ignore the first condition and adds an additional condition to ON clause using AND. I removed join columns from #one-to-many hoping to ignore first condition but it does not. Produced query:
from InvoiceDesigns this_ left outer join UserAccount acc1_ on this_.account_id=acc1_.id and ( acc1_.id=this_.PartnerId )
Thanks in advance

Answer 1

You can try moving the case statement:
SELECT d.Description, d.AccountId, d.PartnerId, a.FormattedName
FROM (SELECT *, CASE
WHEN PartnerId != -1 AND AccountId = 1 THEN PartnerId
WHEN PartnerId = 1 THEN AccountId
ELSE 1
END AS SmartID
FROM InvoiceDesigns) d
INNER JOIN UserAccount a
ON a.id = d.SmartID
WHERE d.AccountId = 1 OR PartnerId = 1
EDIT: This basically leaves you with a straightforward join with an in-line query without a conditional ON statement.

Answer 2

If you only want to map each Design to a single AccountData object, with a single join, but you want to join on either the accountId or partnerId depending on their values, then you should be able to do this by using a join formula. You'll want something like:
#ManyToOne
#JoinColumnsOrFormulas(
{ #JoinColumnOrFormula(
formula = #JoinFormula(
value = "case " +
"when partnerId != -1 and accountId = 1 then partnerId" +
"when partnerId = accountId then accountId " +
"else 1" +
"end",
referencedColumnName="id")) }
)
Note that you need to use the #ManyToOne annotation, even though this is really a one to one association. The join formula won't work if you try to use it on a one to one.
Then you can simply retrieve the data with a normal HQL join:
SELECT d.description, d.accountId, d.partnerId, a.formattedName FROM Design d
inner join d.account a