Inserting records into a MySQL table using Java -

i created database 1 table in mysql:

create database iac_enrollment_system;  use iac_enrollment_system;  create table course(     course_code char(7),     course_desc varchar(255) not null,     course_chair varchar(255),     primary key(course_code) ); 

i tried insert record using java:

// step 1: import required packages import java.sql.*; import java.util.*;  public class sqlinsert { // jdbc driver name , database url static final string jdbc_driver = "com.mysql.jdbc.driver";   static final string db_url = "jdbc:mysql://localhost:3306/iac_enrollment_system";  // database credentials static final string user = "root"; static final string pass = "1234";  public static void main(string[] args) {     connection conn = null;     statement stmt = null;     scanner scn = new scanner(system.in);     string course_code = null, course_desc = null, course_chair = null;      try {         // step 2: register jdbc driver         class.forname("com.mysql.jdbc.driver");          // step 3: open connection         system.out.print("\nconnecting database...");         conn = drivermanager.getconnection(db_url, user, pass);         system.out.println(" success!\n");          // step 4: ask user input         system.out.print("enter course code: ");         course_code = scn.nextline();          system.out.print("enter course description: ");         course_desc = scn.nextline();          system.out.print("enter course chair: ");         course_chair = scn.nextline();          // step 5: excute query         system.out.print("\ninserting records table...");         stmt = conn.createstatement();          string sql = "insert course " +             "values (course_code, course_desc, course_chair)";         stmt.executeupdate(sql);          system.out.println(" success!\n");      } catch(sqlexception se) {         se.printstacktrace();     } catch(exception e) {         e.printstacktrace();     } {         try {             if(stmt != null)                 conn.close();         } catch(sqlexception se) {         }         try {             if(conn != null)                 conn.close();         } catch(sqlexception se) {             se.printstacktrace();         }     }     system.out.println("thank patronage!");   } } 

the output appears return successfully:

but when select mysql, inserted record blank:

why inserting blank record?

no cannot work(not real data):

string sql = "insert course " +         "values (course_code, course_desc, course_chair)";     stmt.executeupdate(sql); 

change to:

string sql = "insert course (course_code, course_desc, course_chair)" +         "values (?, ?, ?)"; 

create preparedstatment sql , insert values index:

preparedstatement preparedstatement = conn.preparestatement(sql); preparedstatement.setstring(1, "test"); preparedstatement.setstring(2, "test2"); preparedstatement.setstring(3, "test3"); preparedstatement.executeupdate();