CURD Operation in java using JDBC

neelakandan@neelakandan-HP-Laptop-15s-eq2xxx:~$ sudo -i -u postgres [sudo] password for neelakandan: postgres@neelakandan-HP-Laptop-15s-eq2xxx:~$ psql psql (16.9 (Ubuntu 16.9-0ubuntu0.24.04.1)) Type "help" for help. postgres=# \c curd_op You are now connected to database "curd_op" as user "postgres". curd_op=# CREATE TABLE users ( id SERIAL PRIMARY KEY, name VARCHAR(100), email VARCHAR(100) ); CREATE TABLE curd_op=# \dt List of relations Schema | Name | Type | Owner --------+-------+-------+---------- public | users | table | postgres (1 row) curd_op=# select * from users; id | name | email ----+------+------- (0 rows) curd_op=# GRANT ALL PRIVILEGES ON TABLE users TO neel0; GRANT curd_op=# ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT ALL ON TABLES TO neel; ALTER DEFAULT PRIVILEGES curd_op=# ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT ALL ON TABLES TO neel0; ALTER DEFAULT PRIVILEGES curd_op=# GRANT USAGE, SELECT, UPDATE ON SEQUENCE users_id_seq TO neel0; GRANT curd_op=# select * from users; id | name | email ----+------+------------- 1 | neel | neel@ex.com (1 row) 

import java.sql.*; 

String url = "jdbc:postgresql://localhost:5432/curd_op"; String user = "neel0"; String pass = "neel0"; Connection con = DriverManager.getConnection(url, user, pass); 

String insert = "insert into users(name,email)values('neel','neel@ex.com')"; con.createStatement().executeUpdate(insert); System.out.println("updated"); ResultSet read = con.createStatement().executeQuery("select * from users"); while (read.next()) { System.out.println(read.getString("name") + " " + read.getString("email")); } 

package Interview_practice; import java.sql.*; public class curd_op { public static void main(String[] args) { String url = "jdbc:postgresql://localhost:5432/curd_op"; String user = "neel0"; String pass = "neel0"; try { Connection con = DriverManager.getConnection(url, user, pass); System.out.println("connected"); String insert = "insert into users(name,email)values('neel','neel@ex.com')"; con.createStatement().executeUpdate(insert); System.out.println("updated"); ResultSet read = con.createStatement().executeQuery("select * from users"); while (read.next()) { System.out.println(read.getString("name") + " " + read.getString("email")); } String update = "update users set name='neelakandan' where id=1"; con.createStatement().executeUpdate(update); System.out.println("updated"); String delete = "delete from users where id =1"; con.createStatement().executeUpdate(delete); System.out.println("deleted"); con.close(); } catch (SQLException e) { e.printStackTrace(); } } } 

 package jdbc; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; public class jdbc_crud { public static void main(String[] args) { String url = "jdbc:postgresql://localhost:5432/mydb"; String user = "neel"; String pass = "neel1862"; String[][] name = { { "Java", "Neel" }, { "Python", "Alice" }, { "C++", "Bob" }, { "Go", "Charlie" }, { "Rust", "David" } }; try { Connection con = DriverManager.getConnection(url, user, pass); Statement s = con.createStatement(); // String insert="insert into users (book,author) values ('java','neel')"; // s.executeUpdate(insert); // System.out.println("insert sucessful"); PreparedStatement ps = con.prepareStatement("insert into users (book,author) values (?,?)"); for (String[] book : name) { ps.setString(1, book[0]); ps.setString(2, book[1]); ps.addBatch(); } ps.executeBatch(); ResultSet rs = s.executeQuery("select * from users"); while (rs.next()) { System.out.println(rs.getString("book") + " " + rs.getString("author")); } String update = "update users set book='notjava' where id=1"; s.executeUpdate(update); System.out.println("updated"); String delete = "delete from users where id=1"; s.executeUpdate(delete); System.out.println("delete"); } catch (SQLException e) { e.printStackTrace(); } } }