eugenp · jzheaux · May 23, 2025 · May 3, 2025
diff --git a/...eptions-2/src/main/java/com/baeldung/hibernate/columnduplicatedmapping/HibernateUtil.java b/...eptions-2/src/main/java/com/baeldung/hibernate/columnduplicatedmapping/HibernateUtil.java
@@ -0,0 +1,39 @@
+package com.baeldung.hibernate.columnduplicatedmapping;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.hibernate.SessionFactory;
+import org.hibernate.boot.Metadata;
+import org.hibernate.boot.MetadataSources;
+import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
+import org.hibernate.service.ServiceRegistry;
+
+public class HibernateUtil {
+    private static SessionFactory sessionFactory;
+
+    public static SessionFactory getSessionFactory() {
+        if (sessionFactory == null) {
+            Map<String, Object> settings = new HashMap<>();
+            settings.put("hibernate.connection.driver_class", "org.h2.Driver");
+            settings.put("hibernate.connection.url", "jdbc:h2:mem:test");
+            settings.put("hibernate.connection.username", "sa");
+            settings.put("hibernate.connection.password", "");
+            settings.put("hibernate.dialect", "org.hibernate.dialect.H2Dialect");
+            settings.put("hibernate.show_sql", "true");
+            settings.put("hibernate.hbm2ddl.auto", "update");
+
+            ServiceRegistry standardRegistry = new StandardServiceRegistryBuilder().applySettings(settings)
+                .build();
+
+            Metadata metadata = new MetadataSources(standardRegistry).addAnnotatedClass(Person.class)
+                .getMetadataBuilder()
+                .build();
+
+            sessionFactory = metadata.getSessionFactoryBuilder()
+                .build();
+        }
+
+        return sessionFactory;
+    }
+}
diff --git a/...ate-exceptions-2/src/main/java/com/baeldung/hibernate/columnduplicatedmapping/Person.java b/...ate-exceptions-2/src/main/java/com/baeldung/hibernate/columnduplicatedmapping/Person.java
@@ -0,0 +1,45 @@
+package com.baeldung.hibernate.columnduplicatedmapping;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+
+@Entity
+public class Person {
+
+    @Id
+    private int id;
+
+    @Column(name = "first_name")
+    private String firstName;
+
+    // switch these two lines to reproduce the exception
+    // @Column(name = "first_name")
+    @Column(name = "last_name")
+    private String lastName;
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+
+}
diff --git a/.../java/com/baeldung/hibernate/columnduplicatedmapping/ColumnDuplicatedMappingUnitTest.java b/.../java/com/baeldung/hibernate/columnduplicatedmapping/ColumnDuplicatedMappingUnitTest.java
@@ -0,0 +1,43 @@
+package com.baeldung.hibernate.columnduplicatedmapping;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import org.hibernate.DuplicateMappingException;
+import org.hibernate.Session;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+class ColumnDuplicatedMappingUnitTest {
+
+    private static Session session;
+
+    @Test
+    @Disabled("Enable this test case once you uncomment the column mapping in Person entity class")
+    void whenDuplicatingColumnMapping_thenThrowDuplicateMappingException() {
+        assertThatThrownBy(() -> {
+            session = HibernateUtil.getSessionFactory()
+                .openSession();
+            session.beginTransaction();
+
+            session.createQuery("FROM Person", Person.class)
+                .list();
+
+            session.close();
+        }).isInstanceOf(DuplicateMappingException.class)
+            .hasMessageContaining("Column 'first_name' is duplicated in mapping for entity");
+    }
+
+    @Test
+    void whenNotDuplicatingColumnMapping_thenCorrect() {
+        session = HibernateUtil.getSessionFactory()
+            .openSession();
+        session.beginTransaction();
+
+        assertThat(session.createQuery("FROM Person", Person.class)
+            .list()).isEmpty();
+
+        session.close();
+    }
+
+}