1. Database - mysql

2. Contents Database –DBMS –Relational model SQL –MySQL

3. Database –a collection of data –Entity, relationship DBMS –Database management system

4. DBMS Why use a DBMS? –efficient access –reduced application development time –data integrity and security –concurrent access –recovery from system crash

5. Relational model Most widely used data model Relation –A set of records –Schema Name of a relation, name of each fields –Instance A table with rows and columns

6. Students(sid:string, sname:string, snum:integer) sidsnamesnum eunyChang Eun Young99 cavalistRyu Han Seung99 netjJaeho Shin00 Fields (attributes, columns) Tuples (records, rows) Field names

7. SQL Structured query language Standard language for interacting with a DBMS Data definition Manipulation

8. MySQL Connect –mysql [–h host] [–u user] [–p[password]] [dbname] >mysql -u root -p test Enter password: ******** Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 14 to server version: 3.23.34a Type 'help;' or '\h' for help. Type '\c' to clear the buffer mysql>

9. MySQL Data definition –CREATE/DROP DATABASE dbname; –SHOW DATABASES; –USE dbname; –CREATE TABLE table_name (field_name type,.., constraints,..); –SHOW TABLES; –SHOW COLUMNS FROM table_name; –DROP TABLE table_name;

10. MySQL Data manipulation –INSERT INTO table_name [(field_name,..)] VALUES (value,..); –DELETE FROM table_name WHERE condition; –UPDATE table_name SET field_name=value,.. [WHERE condition];

11. MySQL Data manipulation(2) –SELECT field_name [as field_name],.. FROM table_name [WHERE condition] [ORDER BY field_name]; –=,, AND, OR, NOT (field_name LIKE “_%….”)

12. MySQL ALTER TABLE –ALTER TABLE table_name [RENAME new_table_name]/ [ADD field_name type]/ [DROP field_name]/ [CHANGE name new_name new_type];

13. mysql> show databases; +----------+ | Database | +----------+ | mysql | | test | +----------+ 2 rows in set (0.00 sec) mysql> use test; Database changed mysql> create database test2; Query OK, 1 row affected (0.00 sec)

14. mysql> CREATE TABLE Students( -> sid VARCHAR(8) NOT NULL, -> sname VARCHAR(20), -> snum INT, -> PRIMARY KEY(sid)); Query OK, 0 rows affected (0.01 sec)

15. MySQL Data Types TypeSizeDescription int tinyint,smallint,mediumint, bigint 4 bytes 1,2,3 and 8 bytes 2^32 values float double 4 bytes 8 bytes Date3 bytesIn the format of YYYY-MM-DD Time3 bytesIn the format of HH:MM:SS char[length] varchar[length] fi String length + 1 byte Fixed length string Variable length from 0 to 255 characters long

16. mysql> show tables; +----------------+ | Tables_in_test | +----------------+ | students | +----------------+ 1 row in set (0.00 sec) mysql> show columns from students; +-------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+-------+ | sid | varchar(8) | | PRI | | | | sname | varchar(20) | YES | | NULL | | | snum | int(11) | YES | | NULL | | +-------+-------------+------+-----+---------+-------+ 3 rows in set (0.01 sec)

17. Primary Key Primary Key is a column or set of columns Uniquely identifies the rest of the data in any giv en row. For Example: in the employee table, employee number is the primary key.

18. Foreign Key A foreign key is a column in a table This column is a primary key of another table Any data in a foreign key column must have co rresponding data in the other table

19. Foreign Key The goal of using foreign keys is that tables can be related without repeating data Note that foreign keys in SQL are used to c heck and enforce referential integrity, not to join tables. If you want to get results from multiple tables from a SELECT stat ement, you do this by performing a join b etween them: SELECT * FROM t1, t2 WHERE t1.id = t2.id;

20. employer Create table with foreign keys create table employee2 ( empno smallint(4) not null, salary float, primary key (empno) ) type = innodb; create table employer ( id smallint(4), employee_no smallint(4), index employ_ind (employee_no), foreign key(employee_no) references employee2(empno) on delete cascade) type=innodb; empno ( PK) salary 100200.85 200129.54 30098.17 idemployee_no(FK) 51100 52100 53200 54300 employee2

21. MySQL Table Types If we want to use Foreign Key –InnoDB tables Otherwise –Default table type, MyISAM In SQL queries you can freely mix In noDB type tables with other table ty pes of MySQL, even within the same query.

22. mysql> INSERT INTO Students -> VALUES ('euny', 'Chang Eun-young', 99); Query OK, 1 row affected (0.00 sec) … mysql> SELECT * FROM Students; +----------+-----------------+------+ | sid | sname | snum | +----------+-----------------+------+ | euny | Chang Eun-young | 99 | | cavalist | Ryu Han Seung | 99 | | netj | Jaeho Shin | 2000 | +----------+-----------------+------+ 3 rows in set (0.00 sec) mysql> DELETE FROM Students -> WHERE sid='euny'; Query OK, 1 row affected (0.00 sec)

23. mysql> UPDATE Students -> SET sid='asdf' -> WHERE sid='euny'; Query OK, 1 row affected (0.00 sec) mysql> SELECT * FROM Students; +----------+-----------------+------+ | sid | sname | snum | +----------+-----------------+------+ | asdf | Chang Eun-young | 99 | | cavalist | Ryu Han Seung | 99 | | netj | Jaeho Shin | 2000 | +----------+-----------------+------+ 1 row in set (0.00 sec)

24. mysql> SELECT * FROM Students ORDER BY sname; +----------+-----------------+------+ | sid | sname | snum | +----------+-----------------+------+ | asdf | Chang Eun-young | 99 | | netj | Jaeho Shin | 2000 | | cavalist | Ryu Han Seung | 99 | +----------+-----------------+------+ 3 rows in set (0.02 sec) mysql> SELECT sname FROM Students WHERE snum=99; +-----------------+ | sname | +-----------------+ | Chang Eun-young | | Ryu Han Seung | +-----------------+ 1 row in set (0.00 sec)

25. Using Connector/J MySQL Connector/J is a native Java driver that converts JDBC (Java Database Connectivity) calls into the network protocol used by the mySQL database. It lets developers working with the Java programming language easily build programs and applets that interact with MySQL and connect all corporate data, even in a heterogeneous environment. MySQL Connector/J is a Type IV JDBC driver and has a complete JDBC feature set that supports the capabilities of MySQL.

26. Using Connector/J Download the software from http://dev.mysql.com/downloads/connector/j/5.0.html MySQL Connector/J is distributed as a zip or.tar.gz archive containing the sources, the class files, and the JAR archive named mysql-connector-java-[version]-bin.jar Install this file in C:\Program Files\Java\jdk1.5.0_07\jre\lib\ext or similar directory on your machine

27. Accessing mySQL from a servlet See Account Information Enter account number to view:

28. Accessing mySQL from a servlet package dbpackage; import java.io.*; import java.sql.*; import javax.servlet.*; import javax.servlet.http.*; public class StudentList extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); PrintWriter out = response.getWriter(); String docType = "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 " + "Transitional//EN\"\n"; String title = "Student List in mySQL"; out.print(docType + " \n" + " " + title + " \n" + " \n" + " Database Results \n");

29. Accessing mySQL from a servlet String driver = "com.mysql.jdbc.Driver"; String url = "jdbc:mysql://localhost/newdb"; String username = "ira"; String password = "mypassword"; String query = "SELECT * from student;"; showTable(driver, url, username, password, query, out); out.println(" "); } public void showTable(String driver, String url, String username, String password, String query, PrintWriter out) { try { // Load database driver if it's not already loaded. Class.forName(driver); // Establish network connection to database. Connection connection = DriverManager.getConnection(url, username, password); // Look up info about the database as a whole. DatabaseMetaData dbMetaData = connection.getMetaData(); out.println(" "); String productName = dbMetaData.getDatabaseProductName(); String productVersion = dbMetaData.getDatabaseProductVersion(); out.println(" Database: " + productName + " Version: " + productVersion + " ");

30. Accessing mySQL from a servlet Statement statement = connection.createStatement(); // Send query to database and store results. ResultSet resultSet = statement.executeQuery(query); // Print results. out.println(" "); ResultSetMetaData resultSetMetaData = resultSet.getMetaData(); int columnCount = resultSetMetaData.getColumnCount(); out.println(" "); // Column index starts at 1 (a la SQL), not 0 (a la Java). for(int i=1; i <= columnCount; i++) { out.print(" " + resultSetMetaData.getColumnName(i)); } out.println(); // Step through each row in the result set. while(resultSet.next()) { out.println(" "); // Step across the row, retrieving the data in each // column cell as a String. }

31. Accessing mySQL from a servlet for(int i=1; i <= columnCount; i++) { out.print(" " + resultSet.getString(i)); } out.println(); } out.println(" "); connection.close(); } catch(ClassNotFoundException cnfe) { System.err.println("Error loading driver: " + cnfe); } catch(SQLException sqle) { System.err.println("Error connecting: " + sqle); } catch(Exception ex) { System.err.println("Error with input: " + ex); }

32. Accessing mySQL from a servlet private static void showResults(ResultSet results) throws SQLException { while(results.next()) { System.out.print(results.getString(1) + " "); } System.out.println(); } private static void printUsage() { System.out.println("Usage: PreparedStatements host " + "dbName username password " + "vendor [print]."); } public void doPost(HttpServletRequest inRequest, HttpServletResponse outResponse) throws ServletException, IOException { doGet(inRequest, outResponse); }