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ImRohitSinghImRohitSingh
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JDBC
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2 files changed

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‎PreparedStatements.java

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import java.sql.*;
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import static java.lang.System.out;
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public class PreparedStatements
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{
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static final String JDBC_DRIVER = "com.mysql.cj.jdbc.Driver";
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static final String JDBC_URL = "jdbc:mysql://localhost:3306/";
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static final String DB_NAME = "jdbc";
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static final String USERNAME = "root";
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static final String PASSWORD = "";
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public static void main(String[] args)
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{
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String createQuery;
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PreparedStatement stmt = null;
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ResultSet rs = null;
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try
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{
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Class.forName(JDBC_DRIVER);
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Connection conn = DriverManager.getConnection(JDBC_URL + DB_NAME, USERNAME, PASSWORD);
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createQuery = "SELECT * FROM STUDENT";
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out.println(createQuery);
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stmt = conn.prepareStatement(createQuery);
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rs = stmt.executeQuery();
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System.out.println("\n\nID \t\t NAMES \t\t\t\t\t JAVA \t\t ALGO \t\t CRYPTO \n");
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while(rs.next())
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System.out.print(rs.getInt(1)+"\t\t"+rs.getString(2)+"\t\t\t\t"+rs.getDouble(3)+"\t\t"+rs.getDouble(4)+"\t\t"+rs.getDouble(5)+"\n");
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stmt = conn.prepareStatement("SELECT * FROM STUDENT WHERE MARKS_JAVA > ? AND MARKS_CRYPTO > ?");
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stmt.setDouble(1, 85);
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stmt.setDouble(2, 80);
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rs = stmt.executeQuery();
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System.out.println("\n\nID \t\t NAMES \t\t\t\t\t JAVA \t\t ALGO \t\t CRYPTO \n");
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while(rs.next())
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System.out.print(rs.getInt(1)+"\t\t"+rs.getString(2)+"\t\t\t\t"+rs.getDouble(3)+"\t\t"+rs.getDouble(4)+"\t\t"+rs.getDouble(5)+"\n");
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}
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catch(ClassNotFoundException cnfe)
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{
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cnfe.printStackTrace();
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}
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catch(SQLException se)
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{
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se.printStackTrace();
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}
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}
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}

‎StudentDatabaseMySQL.java

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import java.sql.*;
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import static java.lang.System.out;
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import java.util.Scanner;
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public class StudentDatabaseMySQL
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{
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static final String JDBC_DRIVER = "com.mysql.cj.jdbc.Driver";
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static final String JDBC_URL = "jdbc:mysql://localhost:3306/";
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static final String DB_NAME = "jdbc";
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static final String USERNAME = "root";
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static final String PASSWORD = "";
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public static void main(String[] args)
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{
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String createQuery, sName;
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ResultSet rs;
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int id, choice, rows, i = 0, ids[], maxInd;
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double mJava, mAlgo, mCrypto, totalM[], max;
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Scanner obj = new Scanner(System.in);
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boolean check, dropped = false;
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try
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{
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Class.forName(JDBC_DRIVER);
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Connection conn = DriverManager.getConnection(JDBC_URL+DB_NAME,USERNAME,PASSWORD);
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Statement stmt = conn.createStatement();
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/*
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// creating table
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createQuery = "CREATE TABLE STUDENT ( " +
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"STUDENT_ID INTEGER PRIMARY KEY,"+
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"STUDENT_NAME VARCHAR(30),"+
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"MARKS_JAVA DOUBLE,"+
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"MARKS_ALGO DOUBLE,"+
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"MARKS_CRYPTO DOUBLE )";
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out.println(createQuery);
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stmt.executeUpdate(createQuery);
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out.println("STUDENT table successfully created...");
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*/
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do
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{
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out.println("\n----MENU----\n1.Display all Records"
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+ "\n2. Add a record\n"
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+ "3. Delete a record\n"
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+ "4. Display records of best student\n"
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+ "5. Scale up marks in Algorithm\n"
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+ "6. Delete all rows\n"
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+ "7. DROP table\n"
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+ "8. Exit\n"
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+ "Enter choice: ");
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choice = obj.nextInt();
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switch(choice)
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{
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case 1: if(dropped)
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{
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out.println("\nSTUDENT table does not exist in database...\n");
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break;
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}
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createQuery = "SELECT * FROM STUDENT";
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rs = stmt.executeQuery(createQuery);
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check = false;
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if(rs.next())
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check = true;
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if(check)
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{
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createQuery = "SELECT * FROM STUDENT";
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out.println("\n"+createQuery+"\n");
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rs = stmt.executeQuery(createQuery);
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System.out.println("\n\nID \t\t NAMES \t\t\t\t\t JAVA \t\t ALGO \t\t CRYPTO \n");
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while(rs.next())
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System.out.print(rs.getInt(1)+"\t\t"+rs.getString(2)+"\t\t\t\t"+rs.getDouble(3)+"\t\t"+rs.getDouble(4)+"\t\t"+rs.getDouble(5)+"\n");
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}
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else
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out.println("\nNothing to display...\n");
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break;
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case 2: if(dropped)
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{
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out.println("\nSTUDENT table does not exist in database...\n");
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break;
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}
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out.println("\nEnter ID: ");
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id = obj.nextInt();
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createQuery = "SELECT * FROM STUDENT WHERE STUDENT_ID = "+id;
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rs = stmt.executeQuery(createQuery);
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check = false;
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if(rs.next())
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check = true;
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if(check)
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out.println("\nID already exists...\n");
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else
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{
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out.println("\nEnter Name: ");
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obj.nextLine();
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sName = obj.nextLine();
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out.println("\nEnter marks in JAVA: ");
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mJava = obj.nextDouble();
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out.println("\nEnter marks in ALGORITHM: ");
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mAlgo = obj.nextDouble();
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out.println("\nEnter marks in CRYPTOGRAPHY: ");
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mCrypto = obj.nextDouble();
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createQuery = "INSERT INTO STUDENT VALUES ( "+id+" , '"+sName+"' , "+mJava+" , "+mAlgo+" , "+mCrypto+" )";
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out.println(createQuery);
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stmt.executeUpdate(createQuery);
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out.println("\nRecord successfully inserted...\n");
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}
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break;
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case 3: if(dropped)
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{
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out.println("\nSTUDENT table does not exist in database...\n");
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break;
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}
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out.println("\nEnter ID: ");
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id = obj.nextInt();
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createQuery = "SELECT * FROM STUDENT WHERE STUDENT_ID = "+id;
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rs = stmt.executeQuery(createQuery);
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check = false;
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if(rs.next())
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check = true;
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if(!check)
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out.println("\nID does not exists...\n");
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else
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{
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createQuery = "DELETE FROM STUDENT WHERE STUDENT_ID = "+id;
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out.println(createQuery);
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stmt.executeUpdate(createQuery);
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out.println("\nRecord successfully deleted...\n");
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}
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break;
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case 4: if(dropped)
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{
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out.println("\nSTUDENT table does not exist in database...\n");
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break;
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}
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createQuery = "SELECT * FROM STUDENT";
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rs = stmt.executeQuery(createQuery);
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check = false;
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if(rs.next())
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check = true;
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if(!check)
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out.println("\nNo data retrieved...\n");
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else
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{
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rows = 0;
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createQuery = "SELECT * FROM STUDENT";
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rs = stmt.executeQuery(createQuery);
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while(rs.next())
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++rows;
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totalM = new double[rows];
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ids = new int[rows];
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createQuery = "SELECT * FROM STUDENT";
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rs = stmt.executeQuery(createQuery);
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while(rs.next())
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{
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totalM[i] = rs.getDouble(3) + rs.getDouble(4) + rs.getDouble(5);
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ids[i] = rs.getInt(1);
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++i;
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}
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i = 0;
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max = totalM[0];
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maxInd = ids[0];
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for( i = 0; i < totalM.length; ++i )
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if( totalM[i] > max )
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{
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max = totalM[i];
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maxInd = ids[i];
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}
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createQuery = "SELECT * FROM STUDENT WHERE STUDENT_ID = "+maxInd;
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out.println(createQuery);
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rs = stmt.executeQuery(createQuery);
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System.out.println("\n\nID \t\t NAME \n");
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while(rs.next())
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System.out.print(rs.getInt(1)+"\t\t"+rs.getString(2)+"\n");
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}
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break;
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case 5: if(dropped)
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{
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out.println("\nSTUDENT table does not exist in database...\n");
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break;
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}
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createQuery = "UPDATE STUDENT SET MARKS_ALGO = MARKS_ALGO + 5 WHERE MARKS_ALGO < 96";
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out.println(createQuery);
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stmt.executeUpdate(createQuery);
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out.println("\nUpdated successfully...\n");
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break;
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case 6: if(dropped)
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{
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out.println("\nSTUDENT table does not exist in database...\n");
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break;
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}
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createQuery = "DELETE FROM STUDENT";
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out.println(createQuery);
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stmt.executeUpdate(createQuery);
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out.println("\nSTUDENT table emptied...\n");
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break;
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case 7: if(!dropped)
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{
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dropped = true;
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createQuery = "DROP TABLE STUDENT";
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out.println(createQuery);
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stmt.executeUpdate(createQuery);
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out.println("STUDENT table successfully dropped...");
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}
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else
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out.println("\nSTUDENT table does not exist in database...\n");
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break;
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case 8: out.println("\nPLEASURE TO SERVE YOU!!\n");
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break;
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default: out.println("\nINVALID CHOICE...\n");
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}
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}
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while(choice != 8);
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}
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catch(ClassNotFoundException cnfe)
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{
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out.println("Error loading MySQL Driver!");
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}
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catch(SQLException se)
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{
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se.printStackTrace();
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out.println("Error accessing Database!");
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}
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}
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}

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