servlets struts hibernate spring maven java
 

JDBC - Delete Records Example


This section gives a precedent on the most proficient method to erase records from a table utilizing JDBC application. Prior to executing following model, ensure you have the accompanying set up −

  • To execute the accompanying model you can supplant the username and password with your genuine client name and password.

  • Your MySQL or whatever database you are utilizing is up and running.

Required Steps

The following advances are required to make another Database utilizing JDBC application −

  • Import the packages: Requires that you incorporate the bundles containing the JDBC classes required for database programming. Regularly, utilizing import java.sql.* will suffice.

  • Register the JDBC driver: Requires that you introduce a driver so you can open an interchanges channel with the database.

  • Open a connection: Requires utilizing the DriverManager.getConnection() strategy to make a Connection object, which speaks to a physical association with a database server.

  • Execute a query: Requires utilizing an object of sort Statement for building and presenting a SQL articulation to erase records from a table. This Query makes utilization of the WHERE statement to erase contingent records.

  • Clean up the environment: Requires expressly shutting all database assets as opposed to depending on the JVM's waste collection.

Sample Code

Copy and glue the accompanying precedent in JDBCExample.java, incorporate and keep running as pursues −

//STEP 1. Import required packages 

import java.sql.*; 

public class JDBCExample { 

//JDBC driver name and database URL 

static final String JDBC_DRIVER = "com.mysql.jdbc.Driver"; 

static final String DB_URL = "jdbc:mysql://localhost/STUDENTS";
    
    
    //Database credentials 

static final String USER = "username"; 

static final String PASS = "password"; 

public static void main(String[] args) { 

Connection conn = null; 

Statement stmt = null; 

try{ 

//STEP 2: Register JDBC driver 

Class.forName("com.mysql.jdbc.Driver"); 

//STEP 3: Open a connection 

System.out.println("Connecting to a chose database..."); 

conn = DriverManager.getConnection(DB_URL, USER, PASS); 

System.out.println("Connected database successfully..."); 

//STEP 4: Execute a query 

System.out.println("Creating statement..."); 

stmt = conn.createStatement(); 

String sql = "DELETE FROM Registration " + 

"WHERE id = 101"; 

stmt.executeUpdate(sql); 

//Now you can separate all the records 

//to see the remaining records 

sql = "SELECT id, first, last, age FROM Registration"; 

ResultSet rs = stmt.executeQuery(sql); 

while(rs.next()){ 

//Retrieve by segment name 

int id = rs.getInt("id"); 

int age = rs.getInt("age"); 

String first = rs.getString("first"); 

String last = rs.getString("last");
    
    //Display values 

System.out.print("ID: " + id); 

System.out.print(", Age: " + age); 

System.out.print(", First: " + first); 

System.out.println(", Last: " + last); 

} 

rs.close(); 

}catch(SQLException se){ 

//Handle blunders for JDBC 

se.printStackTrace(); 

}catch(Exception e){ 

//Handle blunders for Class.forName 

e.printStackTrace(); 

}finally{ 

//at last square used to close resources 

try{ 

if(stmt!=null) 

conn.close(); 

}catch(SQLException se){ 

}//do nothing 

try{ 

if(conn!=null) 

conn.close(); 

}catch(SQLException se){ 

se.printStackTrace(); 

}//end at long last try 

}//end try 

System.out.println("Goodbye!"); 

}//end main 

}//end JDBCExample

Now, let us accumulate the above precedent as pursues −

C:\>javac JDBCExample.java 

C:\>

When you run JDBCExample, it delivers the accompanying outcome −

C:\>java JDBCExample 

Connecting to a chose database...
Connected database successfully...
Creating statement...
ID: 100, Age: 30, First: Zara, Last: Ali
ID: 102, Age: 30, First: Zaid, Last: Khan
ID: 103, Age: 28, First: Sumit, Last: Mittal
Goodbye!
C:\>






© Javacodegeeks © 2019 - 2019
All Right Reserved and you agree to have read and accepted our term and condition.

Python 3