This document discusses Java Database Connectivity (JDBC) and provides examples of connecting to and querying databases using JDBC. It covers the basic steps to connect to a database which include loading the driver, creating a connection, creating statements, and executing queries. Examples are given for connecting to MySQL and retrieving and updating data. Additional topics covered include prepared statements, mapping Java types to SQL types, and using JavaBeans and Data Access Objects for database operations.

1. JDBCJava Database Connectivity
Core Concepts
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Connect with Database
Steps to make a database call:
1. Load Driver
2. Create connection
3. Create statement
4. Execute query and get ResultSet or execute
insert/update/delete query and get number of records affected
Note : Driver jar must be in classpath

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MYSQL – Get Data
public static void main(String args[]) throws Exception{
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection conn =
DriverManager.getConnection("jdbc:mysql://localhost:3306/testdb", "root",“pass");
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("SELECT id, name, color FROM part");
System.out.println("IDtNametColor");
while (rs.next()) {
System.out.print(rs.getString(1));
System.out.print("t" + rs.getString(2));
System.out.println("t" + rs.getString("color"));
}
stmt.close();
conn.close();
}
Load Driver
DB URL Login PWD
SQL
Column value by index
Column value by name

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MYSQL – Insert/Update Data
Class.forName("com.mysql.jdbc.Driver");//load Driver
Connection conn = DriverManager.getConnection( "jdbc:mysql://localhost/testdb", "root", “pass");
//make connection
Statement stmt = conn.createStatement(); //create statement
//execute query
int i= stmt.executeUpdate(“INSERT into part values (4,'plat','Green',1)"); /
System.out.print( i + “ Record(s) Updated ”);
//close statements
stmt.close(); conn.close();

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Prepared Statement
Statement stmt = conn.createStatement();
String sql =“INSERT into part values (4,'plat','Green',1)“;
int i= stmt.executeUpdate(sql);
OR
int id = 4; String name =“plat”; String color = “Green”, int unitId=1;
String sql = “INSERT into part values (“+ id +” , ‘ “ + name + ” ’ ,‘ “+color + ” ’,“+ unitId +”)”;
int i= stmt.executeUpdate(sql);
OR
int id = 4; String name =“plat”; String color = “Green”, int unitId=1;
PreparedStatement ps = conn.prepareStatement(“INSERT into part values (?,?,?,?)")
ps.setInt(1,id);
ps.setString(2,name);
ps.setString(3,color);
ps.setInt(4,unitId);
int i = ps.executeUpdate();

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Mapping Java Types to SQL Types
SQL type Java Type
CHAR, VARCHAR, LONGVARCHAR String
NUMERIC, DECIMAL java.math.BigDecimal
BIT boolean
TINYINT byte
SMALLINT short
INTEGER int
BIGINT long
REAL float
FLOAT, DOUBLE double
BINARY, VARBINARY, LONGVARBINARY byte[]
DATE java.sql.Date
TIME java.sql.Time
TIMESTAMP java.sql.Timestamp
Date + Time
(Nano sec)

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Database Time
Java defines three classes to handle date and time:
 java.sql.Date
o year, month, day
 java.sql.Time
o hours, minutes, seconds
 java.sql.Timestamp
o year, month, day, hours, minutes, seconds, nanoseconds
o By default Timestamp should be used

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Other Databases
 MS SQL
String driver = “com.microsoft.sqlserver.jdbc.SQLServerDriver”;
String url = “jdbc:sqlserver://localhostsqlexpress;user=sa;password=secret”;
Class.forName(driver);
Connection conn = DriverManager.getConnection(url);
 ORACLE
String driver = “oracle.jdbc.OracleDriver”;
String url = “jdbc:oracle://localhost/orcl”;
Class.forName(driver);
Connection conn = DriverManager.getConnection(url,“scott", “tiger");

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Javabean
public class Marksheet {
private String rollNo = null;
private String name = null;
private int chemistry = 0;
private int physics = 0;
private int maths = 0;
public Marksheet(){}//Def
Constructor
public String getRollNO() {
return rollNo ;
}
public void setRollN(String
rollNo) {
this.rollNo = rollNo ;
}
..Other Setter/Getter
Marksheet
-rollNo : String
-name : String
-chemistry : int
-physics : int
-maths:int
+setters
+getters

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Data Access Object
MarksheetDAO
+ add (Marksheet)
+ update (Marksheet)
+ delete (rollNo) : Marksheet
+ get (rollNo) : Marksheet
+getMeritList(): ArrayList
+search(Marksheet)
TestMarksheetDAO
+ testAdd ()
+ testUpdate ()
+ testDelete ()
+ testGet ()
+testGetMeritList()
+testSearch()
+main(String[])

11. Disclaimer
This is an educational presentation to enhance the skill
of computer science students.
This presentation is available for free to computer
science students.
Some internet images from different URLs are used in
this presentation to simplify technical examples and
correlate examples with the real world.
We are grateful to owners of these URLs and pictures.
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12. Thank You!
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