HQL: variable column

Question

I'm able to set variable values for "where" restrictives:

Query criteria = session.createQuery(
  "select test.col1, test.col2, test.col3
  "from Test test " +
  "where test.col = :variableValue ");
criteria.setInteger("variableValue", 10);

But is it possible to set variable column like this?

String variableColumn = "test.col1";
Query criteria = session.createQuery(
  "select test.col1, test.col2, test.col3
  "from Test test " +
  "where :variableColumn = :variableValue ");
criteria.setInteger("variableValue", 10);
criteria.setString("variableColumn", variableColumn);

This is the result:

Exception in thread "main" Hibernate: select .... where ?=? ...
org.hibernate.exception.SQLGrammarException: could not execute query
    at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:92)
    ...
    at _test.TestCriteria.main(TestCriteria.java:44)
Caused by: com.microsoft.sqlserver.jdbc.SQLServerException: Conversion failed when converting the nvarchar value 'test.col1' to data type int.
    ...

UPDATE (working solution):

Query criteria = session.createQuery(
  "select test.col1, test.col2, test.col3
  "from Test test " +
  "where (:value1 is null OR test.col1 = :value1) AND 
         (:value2 is null OR test.col2 = :value2) "

Answer 1

Does this make sense in your application:

String query =  "select test.col1, test.col2, test.col3" + 
  "from Test test " +
  "where {columnName} = :variableValue ";
Object variableValue = // retrieve from somewhere
String columnName = // another retrieve from somewhere
query = query.replace("{columnName}", columName);
// Now continue as always

This is generally a naive query constructor. You may need to refactor this idea to a separate utility/entity-based class to refine (e.g. SQL injection) the queries before execution.