Hibernate Criteria API Equivalent to Oracle's Decode - oracle

Question

What would the equivalent of Oracle's DECODE() function be in the Hibernate Criteria API?
An SQL example of what I need to do:
SELECT DECODE(FIRST_NAME, NULL, LAST_NAME, FIRST_NAME) as NAME ORDER BY NAME;
Which returns LAST_NAME to NAME in the event that FIRST_NAME is NULL.
I would prefer to use the Criteria API but could use HQL if there's no other way.

Answer 1

Check out org.hibernate.criterion.Projections.sqlProjection(...).
Similar to this answer.

Answer 2

For the example you give, you could use COALESCE().
How to simulate NVL in HQL

Answer 3

You can use sqlRestriction to call the native decode function.
session.createCriteria(Table.class).add(Restrictions.sqlRestriction("decode({alias}.firstName,null,
{alias}.lastName,
{alias}.firstName)"))
With HQL, the Oracle dialect already has coalesce and nvl functions, or if you really need decode, you could subclass the dialect and add it as a custom function. I don't know if Hibernate supports a variable length number of arguments like decode does, but worst-case, you could create decode1, decode2, etc to support different numbers of arguments.
Or, if you aren't using the column in a where or group by, you could just bring both attributes back and do the check in Java.

Answer 4

Ended up adding a formula for it:
<property name="name" formula="coalesce(first_name, last_name)"/>
I'm concerned about cross-database problems and possibly efficiency problems with this approach so I'm willing to change the accepted answer.

Answer 5

You can Use Hibernate #Type attribute,Based on your requirement you can customize the annotation and apply on top of the fied. like :
public class PhoneNumberType implements UserType {
#Override
public int[] sqlTypes() {
return new int[]{Types.INTEGER, Types.INTEGER, Types.INTEGER};
}
#Override
public Class returnedClass() {
return PhoneNumber.class;
}
// other methods
}
First, the null SafeGet method:
#Override
public Object nullSafeGet(ResultSet rs, String[] names,
SharedSessionContractImplementor session, Object owner) throws HibernateException,
SQLException {
int countryCode = rs.getInt(names[0]);
if (rs.wasNull())
return null;
int cityCode = rs.getInt(names[1]);
int number = rs.getInt(names[2]);
PhoneNumber employeeNumber = new PhoneNumber(countryCode, cityCode, number);
return employeeNumber;
}
Next, the null SafeSet method:
#Override
public void nullSafeSet(PreparedStatement st, Object value,
int index, SharedSessionContractImplementor session)
throws HibernateException, SQLException {
if (Objects.isNull(value)) {
st.setNull(index, Types.INTEGER);
} else {
PhoneNumber employeeNumber = (PhoneNumber) value;
st.setInt(index,employeeNumber.getCountryCode());
st.setInt(index+1,employeeNumber.getCityCode());
st.setInt(index+2,employeeNumber.getNumber());
}
}
Finally, we can declare our custom PhoneNumberType in our OfficeEmployee entity class:
#Entity
#Table(name = "OfficeEmployee")
public class OfficeEmployee {
#Columns(columns = { #Column(name = "country_code"),
#Column(name = "city_code"), #Column(name = "number") })
#Type(type = "com.baeldung.hibernate.customtypes.PhoneNumberType")
private PhoneNumber employeeNumber;
// other fields and methods
}
This might solve your problem, This will work for all database. if you want more info refer :: https://www.baeldung.com/hibernate-custom-types

Answer 6

If you can use HQL the you can replace DECODE with CASE.
You can update your query from,
SELECT DECODE(FIRST_NAME, NULL, LAST_NAME, FIRST_NAME) as NAME ORDER BY NAME;
to,
SELECT CASE WHEN FIRST_NAME = NULL then LAST_NAME ELSE FIRST_NAME END as NAME ORDER BY NAME;