diff --git a/persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/entity/Account.java b/persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/entity/Account.java
new file mode 100644
index 0000000000..48a98512fa
--- /dev/null
+++ b/persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/entity/Account.java
@@ -0,0 +1,43 @@
+package com.baeldung.jpa.entity;
+
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import javax.persistence.IdClass;
+
+@Entity
+@IdClass(AccountId.class)
+public class Account {
+
+    @Id
+    private String accountNumber;
+
+    @Id
+    private String accountType;
+
+    private String description;
+
+    public String getAccountNumber() {
+        return accountNumber;
+    }
+
+    public void setAccountNumber(String accountNumber) {
+        this.accountNumber = accountNumber;
+    }
+
+    public String getAccountType() {
+        return accountType;
+    }
+
+    public void setAccountType(String accountType) {
+        this.accountType = accountType;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+
+}
diff --git a/persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/entity/AccountId.java b/persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/entity/AccountId.java
new file mode 100644
index 0000000000..091c326367
--- /dev/null
+++ b/persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/entity/AccountId.java
@@ -0,0 +1,52 @@
+package com.baeldung.jpa.entity;
+
+import java.io.Serializable;
+
+public class AccountId implements Serializable {
+
+    private static final long serialVersionUID = 1L;
+
+    private String accountNumber;
+    private String accountType;
+
+    public AccountId() {
+
+    }
+
+    public AccountId(String accountNumber, String accountType) {
+        this.accountNumber = accountNumber;
+        this.accountType = accountType;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((accountNumber == null) ? 0 : accountNumber.hashCode());
+        result = prime * result + ((accountType == null) ? 0 : accountType.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        AccountId other = (AccountId) obj;
+        if (accountNumber == null) {
+            if (other.accountNumber != null)
+                return false;
+        } else if (!accountNumber.equals(other.accountNumber))
+            return false;
+        if (accountType == null) {
+            if (other.accountType != null)
+                return false;
+        } else if (!accountType.equals(other.accountType))
+            return false;
+        return true;
+    }
+
+}
diff --git a/persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/entity/Book.java b/persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/entity/Book.java
new file mode 100644
index 0000000000..460f302e28
--- /dev/null
+++ b/persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/entity/Book.java
@@ -0,0 +1,34 @@
+package com.baeldung.jpa.entity;
+
+import javax.persistence.EmbeddedId;
+import javax.persistence.Entity;
+
+@Entity
+public class Book {
+
+    @EmbeddedId
+    private BookId bookId;
+
+    private String description;
+
+    public Book() {
+
+    }
+
+    public Book(BookId bookId) {
+        this.bookId = bookId;
+    }
+
+    public BookId getBookId() {
+        return bookId;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+
+}
diff --git a/persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/entity/BookId.java b/persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/entity/BookId.java
new file mode 100644
index 0000000000..ff587beaf2
--- /dev/null
+++ b/persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/entity/BookId.java
@@ -0,0 +1,62 @@
+package com.baeldung.jpa.entity;
+
+import java.io.Serializable;
+
+import javax.persistence.Embeddable;
+
+@Embeddable
+public class BookId implements Serializable {
+
+    private static final long serialVersionUID = 1L;
+    private String title;
+    private String language;
+
+    public BookId() {
+
+    }
+
+    public BookId(String title, String language) {
+        this.title = title;
+        this.language = language;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public String getLanguage() {
+        return language;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((language == null) ? 0 : language.hashCode());
+        result = prime * result + ((title == null) ? 0 : title.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        BookId other = (BookId) obj;
+        if (language == null) {
+            if (other.language != null)
+                return false;
+        } else if (!language.equals(other.language))
+            return false;
+        if (title == null) {
+            if (other.title != null)
+                return false;
+        } else if (!title.equals(other.title))
+            return false;
+        return true;
+    }
+
+}
diff --git a/persistence-modules/java-jpa/src/main/resources/META-INF/persistence.xml b/persistence-modules/java-jpa/src/main/resources/META-INF/persistence.xml
index 298397e39d..fc3ff05255 100644
--- a/persistence-modules/java-jpa/src/main/resources/META-INF/persistence.xml
+++ b/persistence-modules/java-jpa/src/main/resources/META-INF/persistence.xml
@@ -1,183 +1,226 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"
-             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-             xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
              http://xmlns.jcp.org/xml/ns/persistence/persistence_2_2.xsd"
-             version="2.2">
+	version="2.2">
 
-    <persistence-unit name="java-jpa-scheduled-day">
-        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
-        <class>com.baeldung.sqlresultsetmapping.ScheduledDay</class>
-        <class>com.baeldung.sqlresultsetmapping.Employee</class>
-        <exclude-unlisted-classes>true</exclude-unlisted-classes>
-        <properties>
-            <property name="javax.persistence.jdbc.driver" value="org.h2.Driver"/>
-            <property name="javax.persistence.jdbc.url"
-                      value="jdbc:h2:mem:test;INIT=RUNSCRIPT FROM 'classpath:database.sql'"/>
-            <property name="javax.persistence.jdbc.user" value="sa"/>
-            <property name="javax.persistence.jdbc.password" value=""/>
-            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/>
-            <!--<property name="hibernate.hbm2ddl.auto" value="create-drop" />-->
-            <property name="show_sql" value="true"/>
-            <property name="hibernate.temp.use_jdbc_metadata_defaults" value="false"/>
-        </properties>
-    </persistence-unit>
+	<persistence-unit name="java-jpa-scheduled-day">
+		<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
+		<class>com.baeldung.sqlresultsetmapping.ScheduledDay</class>
+		<class>com.baeldung.sqlresultsetmapping.Employee</class>
+		<exclude-unlisted-classes>true</exclude-unlisted-classes>
+		<properties>
+			<property name="javax.persistence.jdbc.driver"
+				value="org.h2.Driver" />
+			<property name="javax.persistence.jdbc.url"
+				value="jdbc:h2:mem:test;INIT=RUNSCRIPT FROM 'classpath:database.sql'" />
+			<property name="javax.persistence.jdbc.user" value="sa" />
+			<property name="javax.persistence.jdbc.password" value="" />
+			<property name="hibernate.dialect"
+				value="org.hibernate.dialect.H2Dialect" />
+			<!--<property name="hibernate.hbm2ddl.auto" value="create-drop" /> -->
+			<property name="show_sql" value="true" />
+			<property name="hibernate.temp.use_jdbc_metadata_defaults"
+				value="false" />
+		</properties>
+	</persistence-unit>
 
-    <persistence-unit name="jpa-h2">
-        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
-        <class>com.baeldung.jpa.stringcast.Message</class>
-        <class>com.baeldung.jpa.enums.Article</class>
-        <class>com.baeldung.jpa.enums.CategoryConverter</class>
-        <exclude-unlisted-classes>true</exclude-unlisted-classes>
-        <properties>
-            <property name="javax.persistence.jdbc.driver" value="org.h2.Driver"/>
-            <property name="javax.persistence.jdbc.url" value="jdbc:h2:mem:test"/>
-            <property name="javax.persistence.jdbc.user" value="sa"/>
-            <property name="javax.persistence.jdbc.password" value=""/>
-            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/>
-            <property name="hibernate.hbm2ddl.auto" value="create-drop"/>
-            <property name="show_sql" value="true"/>
-            <property name="hibernate.temp.use_jdbc_metadata_defaults" value="false"/>
-        </properties>
-    </persistence-unit>
+	<persistence-unit name="jpa-h2">
+		<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
+		<class>com.baeldung.jpa.stringcast.Message</class>
+		<class>com.baeldung.jpa.enums.Article</class>
+		<class>com.baeldung.jpa.enums.CategoryConverter</class>
+		<exclude-unlisted-classes>true</exclude-unlisted-classes>
+		<properties>
+			<property name="javax.persistence.jdbc.driver"
+				value="org.h2.Driver" />
+			<property name="javax.persistence.jdbc.url"
+				value="jdbc:h2:mem:test" />
+			<property name="javax.persistence.jdbc.user" value="sa" />
+			<property name="javax.persistence.jdbc.password" value="" />
+			<property name="hibernate.dialect"
+				value="org.hibernate.dialect.H2Dialect" />
+			<property name="hibernate.hbm2ddl.auto" value="create-drop" />
+			<property name="show_sql" value="true" />
+			<property name="hibernate.temp.use_jdbc_metadata_defaults"
+				value="false" />
+		</properties>
+	</persistence-unit>
 
-    <persistence-unit name="jpa-db">
-        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
-        <class>com.baeldung.jpa.model.Car</class>
-        <exclude-unlisted-classes>true</exclude-unlisted-classes>
-        <properties>
-            <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
-            <property name="javax.persistence.jdbc.url" value="jdbc:mysql://127.0.0.1:3306/baeldung"/>
-            <property name="javax.persistence.jdbc.user" value="baeldung"/>
-            <property name="javax.persistence.jdbc.password" value="YourPassword"/>
-            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
-            <property name="hibernate.show_sql" value="true"/>
-        </properties>
-    </persistence-unit>
+	<persistence-unit name="jpa-db">
+		<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
+		<class>com.baeldung.jpa.model.Car</class>
+		<exclude-unlisted-classes>true</exclude-unlisted-classes>
+		<properties>
+			<property name="javax.persistence.jdbc.driver"
+				value="com.mysql.jdbc.Driver" />
+			<property name="javax.persistence.jdbc.url"
+				value="jdbc:mysql://127.0.0.1:3306/baeldung" />
+			<property name="javax.persistence.jdbc.user"
+				value="baeldung" />
+			<property name="javax.persistence.jdbc.password"
+				value="YourPassword" />
+			<property name="hibernate.dialect"
+				value="org.hibernate.dialect.MySQLDialect" />
+			<property name="hibernate.show_sql" value="true" />
+		</properties>
+	</persistence-unit>
 
-    <persistence-unit name="entity-graph-pu" transaction-type="RESOURCE_LOCAL">
-        <class>com.baeldung.jpa.entitygraph.model.Post</class>
-        <class>com.baeldung.jpa.entitygraph.model.User</class>
-        <class>com.baeldung.jpa.entitygraph.model.Comment</class>
-        <exclude-unlisted-classes>true</exclude-unlisted-classes>
-        <properties>
+	<persistence-unit name="entity-graph-pu"
+		transaction-type="RESOURCE_LOCAL">
+		<class>com.baeldung.jpa.entitygraph.model.Post</class>
+		<class>com.baeldung.jpa.entitygraph.model.User</class>
+		<class>com.baeldung.jpa.entitygraph.model.Comment</class>
+		<exclude-unlisted-classes>true</exclude-unlisted-classes>
+		<properties>
 
-            <!--H2-->
-            <property name="javax.persistence.jdbc.driver" value="org.h2.Driver"/>
-            <property name="javax.persistence.jdbc.url"
-                      value="jdbc:h2:mem:entitygraphdb;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE"/>
+			<!--H2 -->
+			<property name="javax.persistence.jdbc.driver"
+				value="org.h2.Driver" />
+			<property name="javax.persistence.jdbc.url"
+				value="jdbc:h2:mem:entitygraphdb;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE" />
 
-            <property name="javax.persistence.schema-generation.database.action" value="drop-and-create"/>
-            <property name="javax.persistence.sql-load-script-source" value="data-init.sql"/>
-        </properties>
-    </persistence-unit>
+			<property
+				name="javax.persistence.schema-generation.database.action"
+				value="drop-and-create" />
+			<property name="javax.persistence.sql-load-script-source"
+				value="data-init.sql" />
+		</properties>
+	</persistence-unit>
 
-    <persistence-unit name="java8-datetime-postgresql" transaction-type="RESOURCE_LOCAL">
-        <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
-        <class>com.baeldung.jpa.datetime.JPA22DateTimeEntity</class>
-        <exclude-unlisted-classes>true</exclude-unlisted-classes>
-        <properties>
-            <property name="javax.persistence.jdbc.driver" value="org.postgresql.Driver"/>
-            <property name="javax.persistence.jdbc.url" value="jdbc:postgresql://localhost:5432/java8-datetime2"/>
-            <property name="javax.persistence.jdbc.user" value="postgres"/>
-            <property name="javax.persistence.jdbc.password" value="postgres"/>
-            <property name="javax.persistence.schema-generation.database.action" value="drop-and-create"/>
+	<persistence-unit name="java8-datetime-postgresql"
+		transaction-type="RESOURCE_LOCAL">
+		<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
+		<class>com.baeldung.jpa.datetime.JPA22DateTimeEntity</class>
+		<exclude-unlisted-classes>true</exclude-unlisted-classes>
+		<properties>
+			<property name="javax.persistence.jdbc.driver"
+				value="org.postgresql.Driver" />
+			<property name="javax.persistence.jdbc.url"
+				value="jdbc:postgresql://localhost:5432/java8-datetime2" />
+			<property name="javax.persistence.jdbc.user"
+				value="postgres" />
+			<property name="javax.persistence.jdbc.password"
+				value="postgres" />
+			<property
+				name="javax.persistence.schema-generation.database.action"
+				value="drop-and-create" />
 
-            <!-- configure logging -->
-            <property name="eclipselink.logging.level" value="INFO"/>
-            <property name="eclipselink.logging.level.sql" value="FINE"/>
-            <property name="eclipselink.logging.parameters" value="true"/>
-        </properties>
-    </persistence-unit>
+			<!-- configure logging -->
+			<property name="eclipselink.logging.level" value="INFO" />
+			<property name="eclipselink.logging.level.sql" value="FINE" />
+			<property name="eclipselink.logging.parameters" value="true" />
+		</properties>
+	</persistence-unit>
 
-    <persistence-unit name="jpa-h2-criteria">
-        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
-        <class>com.baeldung.jpa.criteria.entity.Item</class>
-        <exclude-unlisted-classes>true</exclude-unlisted-classes>
-        <properties>
-            <property name="javax.persistence.jdbc.driver"
-                      value="org.h2.Driver" />
-            <property name="javax.persistence.jdbc.url"
-                      value="jdbc:h2:mem:test" />
-            <property name="javax.persistence.jdbc.user" value="sa" />
-            <property name="javax.persistence.jdbc.password" value="" />
-            <property name="hibernate.dialect"
-                      value="org.hibernate.dialect.H2Dialect" />
-            <property name="hibernate.hbm2ddl.auto" value="create-drop" />
-            <property name="show_sql" value="true" />
-            <property name="hibernate.temp.use_jdbc_metadata_defaults"
-                      value="false" />
-            <property name="javax.persistence.sql-load-script-source" value="item.sql"/>
-        </properties>
-    </persistence-unit>
+	<persistence-unit name="jpa-h2-criteria">
+		<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
+		<class>com.baeldung.jpa.criteria.entity.Item</class>
+		<exclude-unlisted-classes>true</exclude-unlisted-classes>
+		<properties>
+			<property name="javax.persistence.jdbc.driver"
+				value="org.h2.Driver" />
+			<property name="javax.persistence.jdbc.url"
+				value="jdbc:h2:mem:test" />
+			<property name="javax.persistence.jdbc.user" value="sa" />
+			<property name="javax.persistence.jdbc.password" value="" />
+			<property name="hibernate.dialect"
+				value="org.hibernate.dialect.H2Dialect" />
+			<property name="hibernate.hbm2ddl.auto" value="create-drop" />
+			<property name="show_sql" value="true" />
+			<property name="hibernate.temp.use_jdbc_metadata_defaults"
+				value="false" />
+			<property name="javax.persistence.sql-load-script-source"
+				value="item.sql" />
+		</properties>
+	</persistence-unit>
 
-    <persistence-unit name="jpa-query-types">
-        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
-        <class>com.baeldung.jpa.querytypes.UserEntity</class>
-        <exclude-unlisted-classes>true</exclude-unlisted-classes>
-        <properties>
-            <property name="javax.persistence.jdbc.driver"
-                      value="org.h2.Driver" />
-            <property name="javax.persistence.jdbc.url"
-                      value="jdbc:h2:mem:test" />
-            <property name="javax.persistence.jdbc.user" value="sa" />
-            <property name="javax.persistence.jdbc.password" value="" />
-            <property name="hibernate.dialect"
-                      value="org.hibernate.dialect.H2Dialect" />
-            <property name="hibernate.hbm2ddl.auto" value="create-drop" />
-            <property name="show_sql" value="true" />
-            <property name="hibernate.temp.use_jdbc_metadata_defaults"
-                      value="false" />
-            <property name="javax.persistence.sql-load-script-source" value="users.sql"/>
-        </properties>
-    </persistence-unit>
+	<persistence-unit name="jpa-query-types">
+		<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
+		<class>com.baeldung.jpa.querytypes.UserEntity</class>
+		<exclude-unlisted-classes>true</exclude-unlisted-classes>
+		<properties>
+			<property name="javax.persistence.jdbc.driver"
+				value="org.h2.Driver" />
+			<property name="javax.persistence.jdbc.url"
+				value="jdbc:h2:mem:test" />
+			<property name="javax.persistence.jdbc.user" value="sa" />
+			<property name="javax.persistence.jdbc.password" value="" />
+			<property name="hibernate.dialect"
+				value="org.hibernate.dialect.H2Dialect" />
+			<property name="hibernate.hbm2ddl.auto" value="create-drop" />
+			<property name="show_sql" value="true" />
+			<property name="hibernate.temp.use_jdbc_metadata_defaults"
+				value="false" />
+			<property name="javax.persistence.sql-load-script-source"
+				value="users.sql" />
+		</properties>
+	</persistence-unit>
 
-    <persistence-unit name="entity-default-values">
-        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
-        <class>com.baeldung.jpa.defaultvalues.User</class>
-        <exclude-unlisted-classes>true</exclude-unlisted-classes>
-        <properties>
-            <property name="javax.persistence.jdbc.driver" value="org.h2.Driver" />
-            <property name="javax.persistence.jdbc.url" value="jdbc:h2:mem:test" />
-            <property name="javax.persistence.jdbc.user" value="sa" />
-            <property name="javax.persistence.jdbc.password" value="" />
-            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect" />
-            <property name="hibernate.hbm2ddl.auto" value="create-drop" />
-            <property name="show_sql" value="true" />
-            <property name="hibernate.temp.use_jdbc_metadata_defaults" value="false" />
-        </properties>
-    </persistence-unit>
-  
-    <persistence-unit name="jpa-entity-definition">
-        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
-        <class>com.baeldung.jpa.entity.Student</class>
-        <exclude-unlisted-classes>true</exclude-unlisted-classes>
-        <properties>
-            <property name="javax.persistence.jdbc.driver" value="org.h2.Driver" />
-            <property name="javax.persistence.jdbc.url" value="jdbc:h2:mem:test" />
-            <property name="javax.persistence.jdbc.user" value="sa" />
-            <property name="javax.persistence.jdbc.password" value="" />
-            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect" />
-            <property name="hibernate.hbm2ddl.auto" value="create-drop" />
-            <property name="show_sql" value="true" />
-            <property name="hibernate.temp.use_jdbc_metadata_defaults" value="false" />
-        </properties>
-    </persistence-unit>
+	<persistence-unit name="entity-default-values">
+		<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
+		<class>com.baeldung.jpa.defaultvalues.User</class>
+		<exclude-unlisted-classes>true</exclude-unlisted-classes>
+		<properties>
+			<property name="javax.persistence.jdbc.driver"
+				value="org.h2.Driver" />
+			<property name="javax.persistence.jdbc.url"
+				value="jdbc:h2:mem:test" />
+			<property name="javax.persistence.jdbc.user" value="sa" />
+			<property name="javax.persistence.jdbc.password" value="" />
+			<property name="hibernate.dialect"
+				value="org.hibernate.dialect.H2Dialect" />
+			<property name="hibernate.hbm2ddl.auto" value="create-drop" />
+			<property name="show_sql" value="true" />
+			<property name="hibernate.temp.use_jdbc_metadata_defaults"
+				value="false" />
+		</properties>
+	</persistence-unit>
 
-    <persistence-unit name="jpa-projections">
-        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
-        <class>com.baeldung.jpa.projections.Product</class>
-        <exclude-unlisted-classes>true</exclude-unlisted-classes>
-        <properties>
-            <property name="javax.persistence.jdbc.driver" value="org.h2.Driver"/>
-            <property name="javax.persistence.jdbc.url" value="jdbc:h2:mem:test"/>
-            <property name="javax.persistence.jdbc.user" value="sa"/>
-            <property name="javax.persistence.jdbc.password" value=""/>
-            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/>
-            <property name="hibernate.hbm2ddl.auto" value="create-drop"/>
-            <property name="show_sql" value="true"/>
-            <property name="hibernate.temp.use_jdbc_metadata_defaults" value="false"/>
-            <property name="javax.persistence.sql-load-script-source" value="products_jpa.sql"/>
-        </properties>
-    </persistence-unit>
+	<persistence-unit name="jpa-entity-definition">
+		<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
+		<class>com.baeldung.jpa.entity.Student</class>
+		<class>com.baeldung.jpa.entity.Book</class>
+		<class>com.baeldung.jpa.entity.BookId</class>
+		<class>com.baeldung.jpa.entity.Account</class>
+		<class>com.baeldung.jpa.entity.AccountId</class>
+		<exclude-unlisted-classes>true</exclude-unlisted-classes>
+		<properties>
+			<property name="javax.persistence.jdbc.driver"
+				value="org.h2.Driver" />
+			<property name="javax.persistence.jdbc.url"
+				value="jdbc:h2:mem:test" />
+			<property name="javax.persistence.jdbc.user" value="sa" />
+			<property name="javax.persistence.jdbc.password" value="" />
+			<property name="hibernate.dialect"
+				value="org.hibernate.dialect.H2Dialect" />
+			<property name="hibernate.hbm2ddl.auto" value="create-drop" />
+			<property name="show_sql" value="true" />
+			<property name="hibernate.temp.use_jdbc_metadata_defaults"
+				value="false" />
+		</properties>
+	</persistence-unit>
+
+	<persistence-unit name="jpa-projections">
+		<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
+		<class>com.baeldung.jpa.projections.Product</class>
+		<exclude-unlisted-classes>true</exclude-unlisted-classes>
+		<properties>
+			<property name="javax.persistence.jdbc.driver"
+				value="org.h2.Driver" />
+			<property name="javax.persistence.jdbc.url"
+				value="jdbc:h2:mem:test" />
+			<property name="javax.persistence.jdbc.user" value="sa" />
+			<property name="javax.persistence.jdbc.password" value="" />
+			<property name="hibernate.dialect"
+				value="org.hibernate.dialect.H2Dialect" />
+			<property name="hibernate.hbm2ddl.auto" value="create-drop" />
+			<property name="show_sql" value="true" />
+			<property name="hibernate.temp.use_jdbc_metadata_defaults"
+				value="false" />
+			<property name="javax.persistence.sql-load-script-source"
+				value="products_jpa.sql" />
+		</properties>
+	</persistence-unit>
 </persistence>
\ No newline at end of file
diff --git a/persistence-modules/java-jpa/src/test/java/com/baeldung/jpa/entity/CompositeKeysIntegrationTest.java b/persistence-modules/java-jpa/src/test/java/com/baeldung/jpa/entity/CompositeKeysIntegrationTest.java
new file mode 100644
index 0000000000..2d30ebab5e
--- /dev/null
+++ b/persistence-modules/java-jpa/src/test/java/com/baeldung/jpa/entity/CompositeKeysIntegrationTest.java
@@ -0,0 +1,114 @@
+package com.baeldung.jpa.entity;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import javax.persistence.EntityManager;
+import javax.persistence.EntityManagerFactory;
+import javax.persistence.Persistence;
+
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class CompositeKeysIntegrationTest {
+
+    private static final String SAVINGS_ACCOUNT = "Savings";
+    private static final String ACCOUNT_NUMBER = "JXSDF324234";
+    private static final String ENGLISH = "English";
+    private static final String WAR_AND_PEACE = "War and Peace";
+
+    private static EntityManagerFactory emf;
+    private static EntityManager em;
+
+    @BeforeClass
+    public static void setup() {
+        emf = Persistence.createEntityManagerFactory("jpa-entity-definition");
+        em = emf.createEntityManager();
+    }
+
+    @Test
+    public void persistBookWithCompositeKeyThenRetrieveDetails() {
+        Book warAndPeace = createBook();
+        persist(warAndPeace);
+        clearThePersistenceContext();
+        Book book = findBookByBookId();
+        verifyAssertionsWith(book);
+    }
+
+    @Test
+    public void persistAccountWithCompositeKeyThenRetrieveDetails() {
+        Account savingsAccount = createAccount();
+        persist(savingsAccount);
+        clearThePersistenceContext();
+        Account account = findAccountByAccountId();
+        verifyAssertionsWith(account);
+    }
+
+    @AfterClass
+    public static void destroy() {
+        if (em != null) {
+            em.close();
+        }
+        if (emf != null) {
+            emf.close();
+        }
+    }
+
+    private Account createAccount() {
+        Account savingsAccount = new Account();
+        savingsAccount.setAccountNumber(ACCOUNT_NUMBER);
+        savingsAccount.setAccountType(SAVINGS_ACCOUNT);
+        savingsAccount.setDescription("Savings account");
+        return savingsAccount;
+    }
+
+    private void verifyAssertionsWith(Account account) {
+        assertEquals(ACCOUNT_NUMBER, account.getAccountNumber());
+        assertEquals(SAVINGS_ACCOUNT, account.getAccountType());
+    }
+
+    private Account findAccountByAccountId() {
+        return em.find(Account.class, new AccountId(ACCOUNT_NUMBER, SAVINGS_ACCOUNT));
+    }
+
+    private void persist(Account account) {
+        em.getTransaction()
+            .begin();
+        em.persist(account);
+        em.getTransaction()
+            .commit();
+    }
+
+    private Book findBookByBookId() {
+        return em.find(Book.class, new BookId(WAR_AND_PEACE, ENGLISH));
+    }
+
+    private Book createBook() {
+        BookId bookId = new BookId(WAR_AND_PEACE, ENGLISH);
+        Book warAndPeace = new Book(bookId);
+        warAndPeace.setDescription("Novel and Historical Fiction");
+        return warAndPeace;
+    }
+
+    private void verifyAssertionsWith(Book book) {
+        assertNotNull(book);
+        assertNotNull(book.getBookId());
+        assertEquals(WAR_AND_PEACE, book.getBookId()
+            .getTitle());
+        assertEquals(ENGLISH, book.getBookId()
+            .getLanguage());
+    }
+
+    private void persist(Book book) {
+        em.getTransaction()
+            .begin();
+        em.persist(book);
+        em.getTransaction()
+            .commit();
+    }
+
+    private void clearThePersistenceContext() {
+        em.clear();
+    }
+}