Dr. Magdi AMER Unit 2 Introduction to Database

Intro Many programs need to save information on disk. The role of DB system is to provide a layer of abstraction between the program and the database (Save, read, update, delete). First system was released in 1960 by IBM called Information Management System (IMS). It was based on the hierarchical model. 2Dr. Magdi Amer

Intro (Cnt) Hierarchical model has several drawbacks (query, update) Edgar Codd, a British mathematician, created the relational model in 1970, where information is saved into tables. SEQUEL, which was later named SQL (but still pronounced sequel), was developed, based on relational algebra to allow users to define, query and update the database in a standardized way. Codd, with the collaboration of Chris Date, formed their own consulting company and continued to develop the relational standard. 3Dr. Magdi Amer

First Normal Form 4 Project codeDescriptionEmployee name Emp #GradeCost/ hour MonthAllocated Time Prj406E-CommerceSmith127A13012/9950 hour 1/ hour Mark431A22512/9920 hour 1/ hour Tom121A13012/9920 hour 1/ hour Prj012PayrollJack114A13012/9922 hour 1/ hour Green323A22512/9926 hour 1/ hour Dr. Magdi Amer

First Normal Form Each record contains the same number of columns. Each column contain 1 and only 1 value. No information is saved in the order of the records. Each Record must have a key 5 Project code DescriptionEmployee nameEmp #GradeCost/ hourMonthAllocated Time Prj406E-CommerceSmith127A13012/9950 hour Prj406E-CommerceSmith127A1301/ hour Prj406E-CommerceMark431A22512/9920 hour Prj406E-CommerceMark431A2251/ hour Prj406E-CommerceTom121A13012/9920 hour Prj406E-CommerceTom121A1301/ hour Prj012PayrollJack114A13012/9922 hour Prj012PayrollJack114A1301/ hour Prj012PayrollGreen323A22512/9926 hour Prj012PayrollGreen323A2251/ hour Dr. Magdi Amer

Second Normal Form Each column is a function of the entire key, not part of the key. 6 Project code DescriptionEmployee nameEmp #GradeCost/ hourMonthAllocated Time Prj406E-CommerceSmith127A13012/9950 hour Prj406E-CommerceSmith127A1301/ hour Prj406E-CommerceMark431A22512/9920 hour Prj406E-CommerceMark431A2251/ hour Prj406E-CommerceTom121A13012/9920 hour Prj406E-CommerceTom121A1301/ hour Prj012PayrollJack114A13012/9922 hour Prj012PayrollJack114A1301/ hour Prj012PayrollGreen323A22512/9926 hour Prj012PayrollGreen323A2251/ hour Dr. Magdi Amer

Second Normal Form Each column is a function of the entire key, not part of the key. 7Dr. Magdi Amer

Third Normal Form Each column is directly a function of the key. Third normal form is violated when a non-key field is a fact about another non-key field 8Dr. Magdi Amer

Normalization What you need to remember: Normalization is needed: – To save space – To prevent data inconsistency (2 rows supposedly containing the same info but in reality there is a difference in the information stored) – To facilitate update 9Dr. Magdi Amer Student_idStudent_nameCampus_nameCampus_location S101AmalFemale-campusAbedeya S102NohaFemale-campusAbedeya S103HebaFemale-campusDowntown S104MonaFemale-campusDowntown Example of inconsistent data due to lack of normalization

Introduction to SQL 10Dr. Magdi Amer

Introduction to SQL 11Dr. Magdi Amer

Introduction to SQL 12Dr. Magdi Amer

Getting data from normalized tables 13Dr. Magdi Amer Select Employee.Employee_number, Employee.Employee_name, Grade_data.Grade, Grade_data.Cost_per_hour From Employee inner join Grade_data on Grade_data.Grade = Employee.Grade Employee Grade_Data This is done by rebuilding the original table before normalization

Accessing Oracle Express Dr. Magdi Amer14

Dr. Magdi Amer15 Accessing Oracle Express

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Dr. Magdi Amer17 SQL Dev

Dr. Magdi Amer18 SQL Dev

Dr. Magdi Amer19 SQL Dev

Dr. Magdi Amer20 SQL Dev

Dr. Magdi Amer21 SQL Dev

22Dr. Magdi Amer Creating NetBeans App

23Dr. Magdi Amer Making a Connection

24Dr. Magdi Amer Accessing the data from Java

25Dr. Magdi Amer Accessing the data from Java

Making a query 26Dr. Magdi Amer import java.io.*; import java.sql.*; public class DatabaseTest{ public static void main(String[] args){ Connection con= null; Statement s = null; try { con = DatabaseManager.getConnection(); s = con.createStatement(); String query = " SELECT firstName, lastName, sin FROM Employee" ; System.out.println(query); ResultSet result = s.executeQuery(query); String firstName, lastName, sin;

Making a query 27Dr. Magdi Amer while(result.next()) { firstName = result.getString("firstName"); lastName = result.getString("lastName"); sin = result.getString("sin"); System.out.println("first Name = "+firstName+"last Name="+lastName+ "sin ="+sin); }//end while }//end try catch(Exception ex) { System.out.println(ex); } finally { if(con != null) try { con.close(); } catch(Exception ex) { ex.printStackTrace(); } } } // end main } // end class

28Dr. Magdi Amer Writing in a table

29Dr. Magdi Amer Writing in a table

30Dr. Magdi Amer Writing in a table

31Dr. Magdi Amer Writing in a table

32Dr. Magdi Amer Writing in a table try { con = DatabaseManager.getConnection(); s = con.createStatement(); String sql = "create table Data (name varchar (32), id integer);"; int result = s.executeUpdate(sql); sql = "insert into Data (name, id) values ('Tom', 123 );"; result = s.executeUpdate(sql); sql = "insert into Data (name, id) values ('Mike', 123 );"; result = s.executeUpdate(sql); sql = "UPDATE Data SET Data.id = 121 WHERE (Data.name='Mike');"; result = s.executeUpdate(sql); }

33Dr. Magdi Amer Writing in a table catch(Exception ex) { System.out.println(ex); } finally { try { s.close(); con.close(); } catch(Exception e) { System.out.println(e);} } } }

Dr. Magdi Amer34 SQL Injection Consider the following code Normally this code will return the information if the password is correct What will happen if the user enters ' or '1'='1 The executed query will be SELECT firstName, lastName, sin FROM Employee where password = ' ' or '1'='1‘ The previous query result will always be true  hacker can access any record ……… String pass = // read from GUI or web String query = " SELECT firstName, lastName, sin FROM Employee where password = ' "+pass+ " ' "; ResultSet result = s.executeQuery(query); ……………

35Dr. Magdi Amer public void Save() { String query = "INSERT INTO LANGUAGE ( ID, NAME) VALUES (?, ?)"; PreparedStatement s = null; Connection con = null; String url=”…”; try { Connection con = DatabaseManager.getConnection(); s = con.prepareStatement(query); s.setString(2, ""+getName()); //reads it from GUI or web s.setString(1, ""+getId()); // reads it from GUI or web int result = s.executeUpdate(); } catch (SQLException e) { System.err.println(e); } finally { try{ if(s !=null) s.close(); if(con != null) con.close(); } catch(Exception e1) { System.err.println(e1); } } } Prepared Statement

36Dr. Magdi Amer Example

37Dr. Magdi Amer From Java to DB

38Dr. Magdi Amer Saving: Tire

39Dr. Magdi Amer Saving : Motor

40Dr. Magdi Amer Saving : Motor

41Dr. Magdi Amer Saving : Car

42Dr. Magdi Amer Saving : Car

43Dr. Magdi Amer Example: Saving

44Dr. Magdi Amer Loading: Motor

45Dr. Magdi Amer Loading: Tire

46Dr. Magdi Amer Loading: Car

47Dr. Magdi Amer Example: Loading