Add SQL to return all the visited tasks.

src/main/java/cz/muni/ics/kypo/training/adaptive/repository/ParticipantTaskAssignmentRepository.java

 package cz.muni.ics.kypo.training.adaptive.repository;
 
 import cz.muni.ics.kypo.training.adaptive.domain.ParticipantTaskAssignment;
+import cz.muni.ics.kypo.training.adaptive.domain.phase.Task;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.querydsl.QuerydslPredicateExecutor;
 import org.springframework.stereotype.Repository;
 
+import java.util.List;
+
 @Repository
 public interface ParticipantTaskAssignmentRepository extends JpaRepository<ParticipantTaskAssignment, Long>, QuerydslPredicateExecutor<ParticipantTaskAssignment> {
+
+    @Query("SELECT p.task FROM ParticipantTaskAssignment p")
+    List<Task> findAllVisitedTasks();
+
     //TODO provide a SQL commands that returns all the relations between task transitions
+
 }
\ No newline at end of file

src/main/resources/db/migration/V1__db_adaptive_trainings_schema.sql

@@ -48,7 +48,6 @@ create table training_instance (
     training_definition_id int8,
     primary key (training_instance_id),
     foreign key (training_definition_id) references training_definition
-
 );
 
 create table training_instance_user (
@@ -57,7 +56,6 @@ create table training_instance_user (
     primary key (training_instance_id, user_id),
     foreign key (training_instance_id) references training_instance,
     foreign key (user_id) references "user"
-
 );
 
 create table training_run (