diff --git a/data-mapper/src/main/java/com/iluwatar/datamapper/App.java b/data-mapper/src/main/java/com/iluwatar/datamapper/App.java
index 6345b5a4c..8b5853609 100644
--- a/data-mapper/src/main/java/com/iluwatar/datamapper/App.java
+++ b/data-mapper/src/main/java/com/iluwatar/datamapper/App.java
@@ -1,105 +1,104 @@
-/**
- * The MIT License Copyright (c) 2014 Ilkka Seppälä
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
- * associated documentation files (the "Software"), to deal in the Software without restriction,
- * including without limitation the rights to use, copy, modify, merge, publish, distribute,
- * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in all copies or
- * substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
- * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
- * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
- * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
- */
-package com.iluwatar.datamapper;
-
-import java.util.Optional;
-import java.util.UUID;
-
-import org.apache.log4j.Logger;
-
-/**
- * 
- * The Data Mapper (DM) is a layer of software that separates the in-memory objects from the
- * database. Its responsibility is to transfer data between the two and also to isolate them from
- * each other. With Data Mapper the in-memory objects needn't know even that there's a database
- * present; they need no SQL interface code, and certainly no knowledge of the database schema. (The
- * database schema is always ignorant of the objects that use it.) Since it's a form of Mapper ,
- * Data Mapper itself is even unknown to the domain layer.
- * <p>
- * The below example demonstrates basic CRUD operations: select, add, update, and delete.
- * 
- */
-public final class App {
-
-  private static Logger log = Logger.getLogger(App.class);
-
-
-  private static final String DB_TYPE_ORACLE = "Oracle";
-  private static final String DB_TYPE_MYSQL = "MySQL";
-
-
-  /**
-   * Program entry point.
-   * 
-   * @param args command line args.
-   */
-  public static final void main(final String... args) {
-
-    if (log.isInfoEnabled() & args.length > 0) {
-      log.debug("App.main(), db type: " + args[0]);
-    }
-
-    StudentDataMapper mapper = null;
-
-    /* Check the desired db type from runtime arguments */
-    if (args.length == 0) {
-
-      /* Create default data mapper for mysql */
-      mapper = new StudentMySQLDataMapper();
-
-    } else if (args.length > 0 && DB_TYPE_ORACLE.equalsIgnoreCase(args[0])) {
-
-      /* Create new data mapper for mysql */
-      mapper = new StudentMySQLDataMapper();
-
-    } else if (args.length > 0 && DB_TYPE_MYSQL.equalsIgnoreCase(args[0])) {
-
-      /* Create new data mapper for oracle */
-      mapper = new StudentMySQLDataMapper();
-    } else {
-
-      /* Don't couple any Data Mapper to java.sql.SQLException */
-      throw new DataMapperException("Following data source(" + args[0] + ") is not supported");
-    }
-
-    /* Create new student */
-    Student student = new Student(UUID.randomUUID(), 1, "Adam", 'A');
-
-    /* Add student in respectibe db */
-    mapper.insert(student);
-
-    /* Find this student */
-    final Optional<Student> studentToBeFound = mapper.find(student.getGuId());
-
-    if (log.isDebugEnabled()) {
-      log.debug("App.main(), db find returned : " + studentToBeFound);
-    }
-
-    /* Update existing student object */
-    student = new Student(student.getGuId(), 1, "AdamUpdated", 'A');
-
-    /* Update student in respectibe db */
-    mapper.update(student);
-
-    /* Delete student in db */
-    mapper.delete(student);
-  }
-
-  private App() {}
-}
+/**
+ * The MIT License Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
+ * associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute,
+ * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or
+ * substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
+ * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.iluwatar.datamapper;
+
+import java.util.Optional;
+
+import org.apache.log4j.Logger;
+
+/**
+ * 
+ * The Data Mapper (DM) is a layer of software that separates the in-memory objects from the
+ * database. Its responsibility is to transfer data between the two and also to isolate them from
+ * each other. With Data Mapper the in-memory objects needn't know even that there's a database
+ * present; they need no SQL interface code, and certainly no knowledge of the database schema. (The
+ * database schema is always ignorant of the objects that use it.) Since it's a form of Mapper ,
+ * Data Mapper itself is even unknown to the domain layer.
+ * <p>
+ * The below example demonstrates basic CRUD operations: Create, Read, Update, and Delete.
+ * 
+ */
+public final class App {
+
+  private static Logger log = Logger.getLogger(App.class);
+
+
+  private static final String DB_TYPE_ORACLE = "Oracle";
+  private static final String DB_TYPE_MYSQL = "MySQL";
+
+
+  /**
+   * Program entry point.
+   * 
+   * @param args command line args.
+   */
+  public static final void main(final String... args) {
+
+    if (log.isInfoEnabled() & args.length > 0) {
+      log.debug("App.main(), db type: " + args[0]);
+    }
+
+    StudentDataMapper mapper = null;
+
+    /* Check the desired db type from runtime arguments */
+    if (args.length == 0) {
+
+      /* Create default data mapper for mysql */
+      mapper = new StudentMySQLDataMapper();
+
+    } else if (args.length > 0 && DB_TYPE_ORACLE.equalsIgnoreCase(args[0])) {
+
+      /* Create new data mapper for mysql */
+      mapper = new StudentMySQLDataMapper();
+
+    } else if (args.length > 0 && DB_TYPE_MYSQL.equalsIgnoreCase(args[0])) {
+
+      /* Create new data mapper for oracle */
+      mapper = new StudentMySQLDataMapper();
+    } else {
+
+      /* Don't couple any Data Mapper to java.sql.SQLException */
+      throw new DataMapperException("Following data mapping type(" + args[0] + ") is not supported");
+    }
+
+    /* Create new student */
+    Student student = new Student(1, "Adam", 'A');
+
+    /* Add student in respectibe db */
+    mapper.insert(student);
+
+    /* Find this student */
+    final Optional<Student> studentToBeFound = mapper.find(student.getStudentId());
+
+    if (log.isDebugEnabled()) {
+      log.debug("App.main(), db find returned : " + studentToBeFound);
+    }
+
+    /* Update existing student object */
+    student = new Student(student.getStudentId(), "AdamUpdated", 'A');
+
+    /* Update student in respectibe db */
+    mapper.update(student);
+
+    /* Delete student in db */
+    mapper.delete(student);
+  }
+
+  private App() {}
+}
diff --git a/data-mapper/src/main/java/com/iluwatar/datamapper/Student.java b/data-mapper/src/main/java/com/iluwatar/datamapper/Student.java
index 920d4d9ee..2f0c6d0a6 100644
--- a/data-mapper/src/main/java/com/iluwatar/datamapper/Student.java
+++ b/data-mapper/src/main/java/com/iluwatar/datamapper/Student.java
@@ -1,83 +1,103 @@
-/**
- * The MIT License Copyright (c) 2016 Amit Dixit
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
- * associated documentation files (the "Software"), to deal in the Software without restriction,
- * including without limitation the rights to use, copy, modify, merge, publish, distribute,
- * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in all copies or
- * substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
- * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
- * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
- * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
- */
-package com.iluwatar.datamapper;
-
-import java.io.Serializable;
-import java.util.UUID;
-
-public final class Student implements Serializable {
-
-  private static final long serialVersionUID = 1L;
-
-  private UUID guid;
-  private int studentID;
-  private String name;
-  private char grade;
-
-  public Student() {
-    this.guid = UUID.randomUUID();
-  }
-
-  public Student(final UUID guid, final int studentID, final String name, final char grade) {
-    super();
-
-    this.guid = guid;
-    this.studentID = studentID;
-    this.name = name;
-    this.grade = grade;
-  }
-
-
-  public Student(final UUID guid) {
-    this.guid = guid;
-  }
-
-  public final int getStudentId() {
-    return studentID;
-  }
-
-  public final void setStudentId(final int studentID) {
-    this.studentID = studentID;
-  }
-
-  public final String getName() {
-    return name;
-  }
-
-  public final void setName(final String name) {
-    this.name = name;
-  }
-
-  public final char getGrade() {
-    return grade;
-  }
-
-  public final void setGrade(final char grade) {
-    this.grade = grade;
-  }
-
-  public final UUID getGuId() {
-    return guid;
-  }
-
-  @Override
-  public final String toString() {
-    return "Student [guid=" + guid + ", studentID=" + studentID + ", name=" + name + ", grade=" + grade + "]";
-  }
-}
+/**
+ * The MIT License Copyright (c) 2016 Amit Dixit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
+ * associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute,
+ * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or
+ * substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
+ * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.iluwatar.datamapper;
+
+
+import java.io.Serializable;
+
+public final class Student implements Serializable {
+
+  private static final long serialVersionUID = 1L;
+
+  private int studentId;
+  private String name;
+  private char grade;
+
+  public Student() {
+
+  }
+
+  public Student(final int studentId, final String name, final char grade) {
+    super();
+
+    this.studentId = studentId;
+    this.name = name;
+    this.grade = grade;
+  }
+
+  public final int getStudentId() {
+    return studentId;
+  }
+
+  public final void setStudentId(final int studentId) {
+    this.studentId = studentId;
+  }
+
+  public final String getName() {
+    return name;
+  }
+
+  public final void setName(final String name) {
+    this.name = name;
+  }
+
+  public final char getGrade() {
+    return grade;
+  }
+
+  public final void setGrade(final char grade) {
+    this.grade = grade;
+  }
+
+  @Override
+  public boolean equals(final Object inputObject) {
+
+    boolean isEqual = false;
+
+    /* Check if both objects are same */
+    if (this == inputObject) {
+
+      isEqual = true;
+    }
+    /* Check if objects belong to same class */
+    else if (inputObject != null && getClass() == inputObject.getClass()) {
+
+      final Student student = (Student) inputObject;
+
+      /* If student id matched */
+      if (this.getStudentId() == student.getStudentId()) {
+
+        isEqual = true;
+      }
+    }
+    return isEqual;
+  }
+
+  @Override
+  public int hashCode() {
+
+    /* Student id is assumed to be unique */
+    return this.getStudentId();
+  }
+
+  @Override
+  public final String toString() {
+    return "Student [studentId=" + studentId + ", name=" + name + ", grade=" + grade + "]";
+  }
+}
diff --git a/data-mapper/src/main/java/com/iluwatar/datamapper/StudentDataMapper.java b/data-mapper/src/main/java/com/iluwatar/datamapper/StudentDataMapper.java
index 2493a9478..1fa33e067 100644
--- a/data-mapper/src/main/java/com/iluwatar/datamapper/StudentDataMapper.java
+++ b/data-mapper/src/main/java/com/iluwatar/datamapper/StudentDataMapper.java
@@ -1,33 +1,32 @@
-/**
- * The MIT License Copyright (c) 2016 Amit Dixit
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
- * associated documentation files (the "Software"), to deal in the Software without restriction,
- * including without limitation the rights to use, copy, modify, merge, publish, distribute,
- * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in all copies or
- * substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
- * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
- * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
- * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
- */
-package com.iluwatar.datamapper;
-
-import java.util.Optional;
-import java.util.UUID;
-
-public interface StudentDataMapper {
-
-  public Optional<Student> find(final UUID uniqueID) throws DataMapperException;
-
-  public void insert(final Student student) throws DataMapperException;
-
-  public void update(final Student student) throws DataMapperException;
-
-  public void delete(final Student student) throws DataMapperException;
-}
+/**
+ * The MIT License Copyright (c) 2016 Amit Dixit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
+ * associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute,
+ * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or
+ * substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
+ * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.iluwatar.datamapper;
+
+import java.util.Optional;
+
+public interface StudentDataMapper {
+
+  public Optional<Student> find(final int studentId);
+
+  public void insert(final Student student) throws DataMapperException;
+
+  public void update(final Student student) throws DataMapperException;
+
+  public void delete(final Student student) throws DataMapperException;
+}
diff --git a/data-mapper/src/main/java/com/iluwatar/datamapper/StudentMySQLDataMapper.java b/data-mapper/src/main/java/com/iluwatar/datamapper/StudentMySQLDataMapper.java
index 7520bc923..cbb97bfa9 100644
--- a/data-mapper/src/main/java/com/iluwatar/datamapper/StudentMySQLDataMapper.java
+++ b/data-mapper/src/main/java/com/iluwatar/datamapper/StudentMySQLDataMapper.java
@@ -1,160 +1,97 @@
-/**
- * The MIT License Copyright (c) 2016 Amit Dixit
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
- * associated documentation files (the "Software"), to deal in the Software without restriction,
- * including without limitation the rights to use, copy, modify, merge, publish, distribute,
- * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in all copies or
- * substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
- * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
- * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
- * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
- */
-package com.iluwatar.datamapper;
-
-import java.sql.Connection;
-import java.sql.DriverManager;
-import java.sql.PreparedStatement;
-import java.sql.ResultSet;
-import java.sql.SQLException;
-import java.util.Optional;
-import java.util.UUID;
-
-public final class StudentMySQLDataMapper implements StudentDataMapper {
-
-  @Override
-  public final Optional<Student> find(final UUID uniqueID) throws DataMapperException {
-
-    try {
-      /* OracleDriver class cant be initilized directly */
-      Class.forName("oracle.jdbc.driver.OracleDriver");
-
-      /* Create new connection */
-      final Connection connection = DriverManager.getConnection("jdbc:mysql://localhost/MySQL", "username", "password");
-
-      /* Create new Oracle compliant sql statement */
-      final String statement = "SELECT `guid`, `grade`, `studentID`, `name` FROM `students` where `guid`=?";
-      final PreparedStatement dbStatement = connection.prepareStatement(statement);
-
-      /* Set unique id in sql statement */
-      dbStatement.setString(1, uniqueID.toString());
-
-      /* Execute the sql query */
-      final ResultSet rs = dbStatement.executeQuery();
-
-      while (rs.next()) {
-
-        /* Create new student */
-        final Student student = new Student(UUID.fromString(rs.getString("guid")));
-
-        /* Set all values from database in java object */
-        student.setName(rs.getString("name"));
-        student.setGrade(rs.getString("grade").charAt(0));
-        student.setStudentId(rs.getInt("studentID"));
-
-        return Optional.of(student);
-      }
-    } catch (final SQLException | ClassNotFoundException e) {
-
-      /* Don't couple any Data Mapper to java.sql.SQLException */
-      throw new DataMapperException("Error occured reading Students from MySQL data source.", e);
-    }
-
-    /* Return empty value */
-    return Optional.empty();
-  }
-
-  @Override
-  public final void update(final Student student) throws DataMapperException {
-    try {
-
-      /* OracleDriver class cant be initilized directly */
-      Class.forName("oracle.jdbc.driver.OracleDriver");
-
-      /* Create new connection */
-      final Connection connection = DriverManager.getConnection("jdbc:mysql://localhost/MySQL", "username", "password");
-
-      /* Create new Oracle compliant sql statement */
-      final String statement = "UPDATE `students` SET `grade`=?, `studentID`=?, `name`=? where `guid`=?";
-
-      final PreparedStatement dbStatement = connection.prepareStatement(statement);
-
-      /* Set java object values in sql statement */
-      dbStatement.setString(1, Character.toString(student.getGrade()));
-      dbStatement.setInt(2, student.getStudentId());
-      dbStatement.setString(3, student.getName());
-      dbStatement.setString(4, student.getGuId().toString());
-
-      /* Execute the sql query */
-      dbStatement.executeUpdate();
-
-    } catch (final SQLException | ClassNotFoundException e) {
-
-      /* Don't couple any Data Mapper to java.sql.SQLException */
-      throw new DataMapperException("Error occured reading Students from MySQL data source.", e);
-    }
-  }
-
-  @Override
-  public final void insert(final Student student) throws DataMapperException {
-    try {
-
-      /* OracleDriver class cant be initilized directly */
-      Class.forName("oracle.jdbc.driver.OracleDriver");
-
-      /* Create new connection */
-      final Connection connection = DriverManager.getConnection("jdbc:mysql://localhost/MySQL", "username", "password");
-
-      /* Create new Oracle compliant sql statement */
-      final String statement = "INSERT INTO `students` (`grade`, `studentID`, `name`, `guid`) VALUES (?, ?, ?, ?)";
-      final PreparedStatement dbStatement = connection.prepareStatement(statement);
-
-      /* Set java object values in sql statement */
-      dbStatement.setString(1, Character.toString(student.getGrade()));
-      dbStatement.setInt(2, student.getStudentId());
-      dbStatement.setString(3, student.getName());
-      dbStatement.setString(4, student.getGuId().toString());
-
-      /* Execute the sql query */
-      dbStatement.executeUpdate();
-
-    } catch (final SQLException | ClassNotFoundException e) {
-
-      /* Don't couple any Data Mapper to java.sql.SQLException */
-      throw new DataMapperException("Error occured reading Students from MySQL data source.", e);
-    }
-  }
-
-  @Override
-  public final void delete(final Student student) throws DataMapperException {
-    try {
-
-      /* OracleDriver class cant be initilized directly */
-      Class.forName("oracle.jdbc.driver.OracleDriver");
-
-      /* Create new connection */
-      final Connection connection = DriverManager.getConnection("jdbc:mysql://localhost/MySQL", "username", "password");
-
-      /* Create new Oracle compliant sql statement */
-      final String statement = "DELETE FROM `students` where `guid`=?";
-      final PreparedStatement dbStatement = connection.prepareStatement(statement);
-
-      /* Set java object values in sql statement */
-      dbStatement.setString(1, student.getGuId().toString());
-
-      /* Execute the sql query */
-      dbStatement.executeUpdate();
-
-    } catch (final SQLException | ClassNotFoundException e) {
-
-      /* Don't couple any Data Mapper to java.sql.SQLException */
-      throw new DataMapperException("Error occured reading Students from MySQL data source.", e);
-    }
-  }
-}
+/**
+ * The MIT License Copyright (c) 2016 Amit Dixit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
+ * associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute,
+ * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or
+ * substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
+ * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.iluwatar.datamapper;
+
+import java.util.List;
+import java.util.Optional;
+
+public final class StudentMySQLDataMapper implements StudentDataMapper {
+
+  /* Note: Normally this would be in the form of an actual database */
+  private List<Student> students;
+
+  @Override
+  public final Optional<Student> find(final int studentId) {
+
+    /* Compare with existing students */
+    for (final Student student : this.students) {
+
+      /* Check if student is found */
+      if (student.getStudentId() == studentId) {
+
+        return Optional.of(student);
+      }
+    }
+
+    /* Return empty value */
+    return Optional.empty();
+  }
+
+  @Override
+  public final void update(final Student studentToBeUpdated) throws DataMapperException {
+
+
+    /* Check with existing students */
+    if (this.students.contains(studentToBeUpdated)) {
+
+      /* Get the index of student in list */
+      final int index = this.students.indexOf(studentToBeUpdated);
+
+      /* Update the student in list */
+      this.students.set(index, studentToBeUpdated);
+
+    } else {
+
+      /* Throw user error */
+      throw new DataMapperException("Student [" + studentToBeUpdated.getName() + "] is not found");
+    }
+  }
+
+  @Override
+  public final void insert(final Student studentToBeInserted) throws DataMapperException {
+
+    /* Check with existing students */
+    if (!this.students.contains(studentToBeInserted)) {
+
+      /* Add student in list */
+      this.students.add(studentToBeInserted);
+
+    } else {
+
+      /* Throw user error */
+      throw new DataMapperException("Student already [" + studentToBeInserted.getName() + "] exists");
+    }
+  }
+
+  @Override
+  public final void delete(final Student studentToBeDeleted) throws DataMapperException {
+
+    /* Check with existing students */
+    if (this.students.contains(studentToBeDeleted)) {
+
+      /* Delete the student from list */
+      this.students.remove(studentToBeDeleted);
+
+    } else {
+
+      /* Throw user error */
+      throw new DataMapperException("Student [" + studentToBeDeleted.getName() + "] is not found");
+    }
+  }
+}
diff --git a/data-mapper/src/main/java/com/iluwatar/datamapper/StudentOracleDataMapper.java b/data-mapper/src/main/java/com/iluwatar/datamapper/StudentOracleDataMapper.java
index 0b6b7ebbf..6abf1c55a 100644
--- a/data-mapper/src/main/java/com/iluwatar/datamapper/StudentOracleDataMapper.java
+++ b/data-mapper/src/main/java/com/iluwatar/datamapper/StudentOracleDataMapper.java
@@ -1,160 +1,97 @@
-/**
- * The MIT License Copyright (c) 2016 Amit Dixit
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
- * associated documentation files (the "Software"), to deal in the Software without restriction,
- * including without limitation the rights to use, copy, modify, merge, publish, distribute,
- * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in all copies or
- * substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
- * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
- * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
- * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
- */
-package com.iluwatar.datamapper;
-
-import java.sql.Connection;
-import java.sql.DriverManager;
-import java.sql.PreparedStatement;
-import java.sql.ResultSet;
-import java.sql.SQLException;
-import java.util.Optional;
-import java.util.UUID;
-
-public final class StudentOracleDataMapper implements StudentDataMapper {
-
-  @Override
-  public final Optional<Student> find(final UUID uniqueID) throws DataMapperException {
-
-    try {
-      /* OracleDriver class cant be initilized directly */
-      Class.forName("oracle.jdbc.driver.OracleDriver");
-
-      /* Create new connection */
-      final Connection connection = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:Oracle", "username", "password");
-
-      /* Create new Oracle compliant sql statement */
-      final String statement = "SELECT `guid`, `grade`, `studentID`, `name` FROM `students` where `guid`=?";
-      final PreparedStatement dbStatement = connection.prepareStatement(statement);
-
-      /* Set unique id in sql statement */
-      dbStatement.setString(1, uniqueID.toString());
-
-      /* Execute the sql query */
-      final ResultSet rs = dbStatement.executeQuery();
-
-      while (rs.next()) {
-
-        /* Create new student */
-        final Student student = new Student(UUID.fromString(rs.getString("guid")));
-
-        /* Set all values from database in java object */
-        student.setName(rs.getString("name"));
-        student.setGrade(rs.getString("grade").charAt(0));
-        student.setStudentId(rs.getInt("studentID"));
-
-        return Optional.of(student);
-      }
-    } catch (final SQLException | ClassNotFoundException e) {
-
-      /* Don't couple any Data Mapper to java.sql.SQLException */
-      throw new DataMapperException("Error occured reading Students from Oracle data source.", e);
-    }
-
-    /* Return empty value */
-    return Optional.empty();
-  }
-
-  @Override
-  public final void update(final Student student) throws DataMapperException {
-    try {
-
-      /* OracleDriver class cant be initilized directly */
-      Class.forName("oracle.jdbc.driver.OracleDriver");
-
-      /* Create new connection */
-      final Connection connection = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:Oracle", "username", "password");
-
-      /* Create new Oracle compliant sql statement */
-      final String statement = "UPDATE `students` SET `grade`=?, `studentID`=?, `name`=? where `guid`=?";
-
-      final PreparedStatement dbStatement = connection.prepareStatement(statement);
-
-      /* Set java object values in sql statement */
-      dbStatement.setString(1, Character.toString(student.getGrade()));
-      dbStatement.setInt(2, student.getStudentId());
-      dbStatement.setString(3, student.getName());
-      dbStatement.setString(4, student.getGuId().toString());
-
-      /* Execute the sql query */
-      dbStatement.executeUpdate();
-
-    } catch (final SQLException | ClassNotFoundException e) {
-
-      /* Don't couple any Data Mapper to java.sql.SQLException */
-      throw new DataMapperException("Error occured reading Students from Oracle data source.", e);
-    }
-  }
-
-  @Override
-  public final void insert(final Student student) throws DataMapperException {
-    try {
-
-      /* OracleDriver class cant be initilized directly */
-      Class.forName("oracle.jdbc.driver.OracleDriver");
-
-      /* Create new connection */
-      final Connection connection = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:Oracle", "username", "password");
-
-      /* Create new Oracle compliant sql statement */
-      final String statement = "INSERT INTO `students` (`grade`, `studentID`, `name`, `guid`) VALUES (?, ?, ?, ?)";
-      final PreparedStatement dbStatement = connection.prepareStatement(statement);
-
-      /* Set java object values in sql statement */
-      dbStatement.setString(1, Character.toString(student.getGrade()));
-      dbStatement.setInt(2, student.getStudentId());
-      dbStatement.setString(3, student.getName());
-      dbStatement.setString(4, student.getGuId().toString());
-
-      /* Execute the sql query */
-      dbStatement.executeUpdate();
-
-    } catch (final SQLException | ClassNotFoundException e) {
-
-      /* Don't couple any Data Mapper to java.sql.SQLException */
-      throw new DataMapperException("Error occured reading Students from Oracle data source.", e);
-    }
-  }
-
-  @Override
-  public final void delete(final Student student) throws DataMapperException {
-    try {
-
-      /* OracleDriver class cant be initilized directly */
-      Class.forName("oracle.jdbc.driver.OracleDriver");
-
-      /* Create new connection */
-      final Connection connection = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:Oracle", "username", "password");
-
-      /* Create new Oracle compliant sql statement */
-      final String statement = "DELETE FROM `students` where `guid`=?";
-      final PreparedStatement dbStatement = connection.prepareStatement(statement);
-
-      /* Set java object values in sql statement */
-      dbStatement.setString(1, student.getGuId().toString());
-
-      /* Execute the sql query */
-      dbStatement.executeUpdate();
-
-    } catch (final SQLException | ClassNotFoundException e) {
-
-      /* Don't couple any Data Mapper to java.sql.SQLException */
-      throw new DataMapperException("Error occured reading Students from Oracle data source.", e);
-    }
-  }
-}
+/**
+ * The MIT License Copyright (c) 2016 Amit Dixit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
+ * associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute,
+ * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or
+ * substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
+ * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.iluwatar.datamapper;
+
+import java.util.List;
+import java.util.Optional;
+
+public final class StudentOracleDataMapper implements StudentDataMapper {
+
+  /* Note: Normally this would be in the form of an actual database */
+  private List<Student> students;
+
+  @Override
+  public final Optional<Student> find(final int studentId) {
+
+    /* Compare with existing students */
+    for (final Student student : this.students) {
+
+      /* Check if student is found */
+      if (student.getStudentId() == studentId) {
+
+        return Optional.of(student);
+      }
+    }
+
+    /* Return empty value */
+    return Optional.empty();
+  }
+
+  @Override
+  public final void update(final Student studentToBeUpdated) throws DataMapperException {
+
+
+    /* Check with existing students */
+    if (this.students.contains(studentToBeUpdated)) {
+
+      /* Get the index of student in list */
+      final int index = this.students.indexOf(studentToBeUpdated);
+
+      /* Update the student in list */
+      this.students.set(index, studentToBeUpdated);
+
+    } else {
+
+      /* Throw user error */
+      throw new DataMapperException("Student [" + studentToBeUpdated.getName() + "] is not found");
+    }
+  }
+
+  @Override
+  public final void insert(final Student studentToBeInserted) throws DataMapperException {
+
+    /* Check with existing students */
+    if (!this.students.contains(studentToBeInserted)) {
+
+      /* Add student in list */
+      this.students.add(studentToBeInserted);
+
+    } else {
+
+      /* Throw user error */
+      throw new DataMapperException("Student already [" + studentToBeInserted.getName() + "] exists");
+    }
+  }
+
+  @Override
+  public final void delete(final Student studentToBeDeleted) throws DataMapperException {
+
+    /* Check with existing students */
+    if (this.students.contains(studentToBeDeleted)) {
+
+      /* Delete the student from list */
+      this.students.remove(studentToBeDeleted);
+
+    } else {
+
+      /* Throw user error */
+      throw new DataMapperException("Student [" + studentToBeDeleted.getName() + "] is not found");
+    }
+  }
+}