jpql中select的case语句

Question

I have tried the following but not working.

String mainQuerySt = "select o.progressStatus, "
+ " CASE WHEN o.assigneeEmployee IS NOT NULL THEN o.assigneeEmployee.fullNameSt ELSE '' END as assignee "
+ " from Tt o"

em.createQuery(mainQuerySt).getResultList();

What is wrong with this? Actually, I want to show assigneeEmployee full name if it is not null and otherwise an empty string.

I am using EclipseLink v2.1 as JPA

Thanks in advnace.

EclipseLink Tutorial

Answer 1

You are using o.assigneeEmployee IS NOT NULL, and I assume o.assigneeEmployee is a relationship. Using dot notation forces an inner join, which then will filter out nulls. Try

String mainQuerySt = "select o.progressStatus, "
+ " CASE WHEN assigneeEmployee IS NOT NULL THEN assigneeEmployee.fullNameSt ELSE '' END as assignee "
+ " from Tt o left outer join o.assigneeEmployee assigneeEmployee"

If it does not return the results expected, then you will need to turn on SQL logging to see the SQL produced, and show the results you do expect.