JDBC 3.0. Java Database Connectivity. 1 Java

Transcription

1 JDBC 3.0 Database Connectivity 1

2 Contents 1 JDBC API 2 JDBC Architecture 3 Steps to code 4 Code 5 How to configure the DSN for ODBC Driver for MS-Access 6 Driver Types 7 JDBC-ODBC Bridge 8 Disadvantages 9 Type2- Part, Part Native Driver 10 Drivers currently in use 2

3 Contents 11 Load the driver and get Connection 12 Obtaining Statement 13 Statement 14 Simple ResultSet methods 15 Advanced ResultSet 16 Connection object s parameterized createstatement() methods 17 Code to work with advanced ResulSet 18 More ResultSet methods 19 PreparedStatement 20 Methods 3

4 Contents 21 CallableStatement 22 Create the following Stored Procedure in Oracle 23 Code to call the stored procedure 24 Transaction support 4

5 Know The JDBC API. The different kinds of drivers What ResultSet is Different types of statements Transaction Support 5

6 Be Able To Use JDBC to create data interactive programs Implement Transaction Support 6

7 JDBC API JDBC 3.0 part of J2SE 5.0, is an API that provides a set of generic database access methods for SQL compliant relational databases. Our focus JDBC 3.0 java.sql core javax.sql extension 7

8 JDBC Architecture 8

9 Steps to code Load the driver Obtain connection Create and execute statements [Use result sets to navigate the results] Close the connection 9

10 Code import java.sql.*; public class ODBCMain{ Connection con; public ODBCMain() { Data source name (DSN) try { String url = "jdbc:odbc:sample"; Load the JDBC-ODBC bridge driver Class.forName("sun.jdbc.odbc.JdbcOdbcDr iver"); con = DriverManager.getConnection(url); Folder 1 Obtain the connection to the database 10

11 Create and execute sql statements Statement stmt = con.createstatement(); stmt.executeupdate("insert INTO student VALUES('Shreyas',1234)" ); con.close(); } Close the connection catch(exception e) { e.printstacktrace(); throw new RuntimeException(); } } public static void main(string str[]){ new ODBCMain(); }} 11

12 How to configure the DSN for ODBC Driver for MS- Access In control panel locate Data Sources (ODBC) icon Create the MS-Access table sample with name(text) and id(number, primary key). Double-click the icon and click on add button in the User DSN tab. Select Microsoft Access Driver and click Finish click 12

13 Enter DSN name as sample (same name you have given in the code) and click Select. Browse through and get the access file and click ok. Click ok on next two screens and come out of the control panel. click 13

14 Driver Types JDBC driver are used to translate JDBC calls into vendor-specific database calls. Types of driver Type 1- JDBC-ODBC Bridge Type 2- Part, Part Native Driver Type 3- Intermediate Database Access Server Type 4- Pure Drivers 14

15 JDBC-ODBC Bridge application Database JDBC API JDBC-ODBC Bridge ODBC API ODBC Layer 15

16 Disadvantages ODBC uses a C. Calls from to native C code have a number of drawbacks in the security, robustness, and automatic portability of applications. Multiple layers of indirection leads to inefficiency. 16

17 Type2- Part, Part Native Driver application Database JDBC API JDBC Driver Vendor Specific API 17

18 Drivers currently in use Type 4 Two-tier Direct to database Pure Driver Type 3 Three-tier JDBC-Net pure Driver for Database middleware 18

19 application JDBC Driver Manager or Data Source Object Pure Driver JDBC-Net Pure Driver Database middleware Database 19

20 Load the driver and get Connection Register (Load) the driver with the application: Class.forName("oracle.jdbc.OracleDriver" ); Or DriverManager.registerDriver( new oracle.jdbc.oracledriver()); Getting Connection: DriverManager.getConnection(url); Or DriverManager.getConnection(url,username, password); 20

21 Obtaining Statement Connection createstatement() Statement preparestatement(string s) PreparedStatement preparecall(string sql) CallableStatement 21

22 Statement public ResultSet executequery(string sql) throws SQLException SELECT Query public int executeupdate(string sql) throws SQLException INSERT, UPDATE, DELETE, CREATE and DROP. 22

23 Simple ResultSet methods boolean next() throws SQLException void close() throws SQLException XXX getxxx(int columnindex) throws SQLException where XXX is any primitive type, String, java.sql.date, Object. 23

24 import java.sql.*; public class ODBCMain{ Connection con; public ODBCMain() { try { String url = "jdbc:odbc:sample"; Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); con = DriverManager.getConnection(url); Statement stmt = con.createstatement(); ResultSet rs = stmt.executequery("select * FROM student"); Folder 2 24

25 while (rs.next() ) { String a= rs.getstring(1); int i = rs.getint(2); String oneline = "name " + a + "id= " + i; System.out.println(oneLine); } } catch(exception e){e.printstacktrace(); } } public static void main(string str[]){ new ODBCMain(); }} 25

26 Advanced ResultSet A default ResultSet object is not updatable and has a cursor that moves forward only. In order to have ResultSet which are scrollable and updatable first we need to use a different createstatement() method. 26

27 Connection object s parameterized createstatement() methods public Statement createstatement(int ressettype,int ressetconcurrency) throws SQLException ressettype : ResultSet.TYPE_FORWARD_ONLY ResultSet.TYPE_SCROLL_INSENSITIVE ResultSet.TYPE_SCROLL_SENSITIVE ressetconcurrency : ResultSet.CONCUR_READ_ONLY ResultSet.CONCUR_UPDATABLE 27

28 Code to work with advanced ResulSet import java.sql.*; public class OracleRS{ Connection con; static final String url public OracleRS() { Oracle server machine name try{ Class.forName("oracle.jdbc.OracleDriver"); con = DriverManager.getConnection(url,"SYSTEM", "admin"); User name Statement stmt = con.createstatement(resultset.type_scroll _INSENSITIVE, ResultSet.CONCUR_UPDATABLE); URL for oracle database port Folder 3 sid password 28

29 ResultSet rs = stmt.executequery("select name, id FROM stud"); rs.absolute(2); moves the cursor 2nd row rs.updatestring(1, BLACK"); rs.updaterow(); } con.close(); catch(exception e) { e.printstacktrace(); }} public static void main(string str[]) { new OracleRS();}} updates the row 29

30 More ResultSet methods boolean absolute(int row) void afterlast() void beforefirst() void cancelrowupdates() void deleterow() void insertrow() boolean isafterlast(), boolean isbeforefirst(), booleanisfirst(), booleanislast() void movetocurrentrow() void movetoinsertrow() void updaterow() All throw SQLException 30

31 31

32 PreparedStatement Subclasses from Statement If the same sql statement is executed many times it is more efficient to use a prepared statement. It enables a SQL statement to contain parameters like functions. So same statement can be executed for different set of values. 32

33 public void clearparameters() throws SQLException void setbyte(int parameterindex, byte x) void setint(int parameterindex, int x) void setshort(int parameterindex, short x) void setlong(int parameterindex, long x) void setdouble(int parameterindex, double x) void setfloat(int parameterindex, float x) void setdate void setint(int parameterindex, java.sql.date d) void setstring(int parameterindex, String x) Methods 33

34 Example Table name: BookIssue Column name Type Length BOOKID NUM 10 REGNO VARCHAR 10 We will use PreaparedStatemen t to insert into the this table. The program will also demonstrate how to work with Dates ISSUEDATE DATE 4 RETURNDATE DATE 4 34

35 import java.sql.*; public class PrepAccess{ Connection con; public PrepAccess() { Connection con; public PrepAccess() { try { Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); con= DriverManager.getConnection("jdbc:odbc:book"); PreparedStatement stmt = con.preparestatement("insert INTO BookIssue VALUES(?,?,?,?)"); stmt.setint(1,10005); stmt.setstring(2,"to kill a mocking bird"); Folder 4 35

36 java.util.calendar c=java.util.calendar.getinstance(); c.clear(); c.set(2004,9,25); stmt.setdate(3,new java.sql.date((c.gettime()).gettime())); c.set(2004,9,27); stmt.setdate(4,new java.sql.date((c.gettime()).gettime())); stmt.executeupdate(); stmt.close();} catch(exception e) {} public static void main(string str[]){ new PrepAccess(); }} 36

37 CallableStatement Used to execute stored-procedure. {call <procedure-name>[<arg1>,<arg2>,...]} IN parameter values are set using the set methods inherited from PreparedStatement. All OUT parameters must be registered before a stored procedure is executed. The example in the next slide demonstrates the use of Callable statement, input and output parameters. 37

38 Create the following Stored Procedure in Oracle CREATE OR REPLACE PROCEDURE GETSTUD(id1 IN NUMBER, nm OUT VARCHAR) AS BEGIN SELECT NAME INTO nm FROM stud WHERE ID=id1; END; 38

39 Code to call the stored procedure import java.sql.*; class CallableOracle{ public static void main(string argv[]) { try { String url ="jdbc:oracle:thin:@deepa.:1521:sample"; Class.forName("oracle.jdbc.OracleDriver"); Connection con = DriverManager.getConnection(url,"SYSTEM"," admin"); CallableStatement c=con.preparecall("{call GETSTUD(?,?)}"); Folder 5 39

40 First parameter String name=null; c.setint(1,124); Value c.registeroutparameter( 2,java.sql.Types.VARCHAR); c.executeupdate(); name=c.getstring(2); System.out.println(" completed successfully "+ name); } catch (Exception e) { System.out.println(e.toString()); }} } 40

41 Transaction support Methods in Connection class helps to demarcate the set of statements into a transaction. public void setautocommit(boolean autocommit) throws SQLException public void rollback() SQLException public void commit() throws SQLException throws 41

42 To understand transactions we will use two tables Login ( id, login, password) and Student (id, name). Insertion of student data will require us to insert data either into both the tables or in none of them in case there is an error. 42

43 import java.sql.*; class Trans{ public static void insert(string login, String pass,int id, String name){ Connection con=null; try { String url = "jdbc:odbc:sample"; Class.forName("sun.jdbc.odbc.JdbcOdbcDriver "); con = DriverManager.getConnection(url); Statement st=con.createstatement(); con.setautocommit(false); st.executeupdate("insert INTO Login VALUES("+ id+ ",'"+login+"','"+pass+"')"); st.executeupdate("insert INTO Student VALUES('"+name+"',"+id+")"); con.commit(); Folder 6 transaction 43

44 con.close(); } catch(exception e) { try{ System.out.println("Rolling back Exception :" + e.tostring()); con.rollback(); e.printstacktrace();} catch(exception e1){} } } public static void main(string[] s){ // insert("emily", "danger", 1,"Emily"); insert("susan", "danger", 1234,"Susan"); } } 44

45 Set the id as the primary key for the Student and login as primary key for table Login. Test the application by giving duplicate id values a) without transaction statements b) with transaction statements 45