[java] Inserting records into a MySQL table using Java

I created a database with one 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 to insert a record using Java:

// STEP 1: Import required packages
import java.sql.*;
import java.util.*;

public class SQLInsert {
// JDBC driver name and 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 a connection
        System.out.print("\nConnecting to database...");
        conn = DriverManager.getConnection(DB_URL, USER, PASS);
        System.out.println(" SUCCESS!\n");

        // STEP 4: Ask for 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 into table...");
        stmt = conn.createStatement();

        String sql = "INSERT INTO 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();
    } finally {
        try {
            if(stmt != null)
                conn.close();
        } catch(SQLException se) {
        }
        try {
            if(conn != null)
                conn.close();
        } catch(SQLException se) {
            se.printStackTrace();
        }
    }
    System.out.println("Thank you for your patronage!");
  }
}

The output appears to return successfully:

But when I select from MySQL, the inserted record is blank:

Why is it inserting a blank record?

There is a mistake in your insert statement chage it to below and try : String sql = "insert into table_name values ('" + Col1 +"','" + Col2 + "','" + Col3 + "')";

This should work for any table, instead of hard-coding the columns.

//Source details_x000D_
    String sourceUrl = "jdbc:oracle:thin:@//server:1521/db";_x000D_
    String sourceUserName = "src";_x000D_
    String sourcePassword = "***";_x000D_
_x000D_
    // Destination details_x000D_
    String destinationUserName = "dest";_x000D_
    String destinationPassword = "***";_x000D_
    String destinationUrl = "jdbc:mysql://server:3306/db";_x000D_
_x000D_
    Connection srcConnection = getSourceConnection(sourceUrl, sourceUserName, sourcePassword);_x000D_
    Connection destConnection = getDestinationConnection(destinationUrl, destinationUserName, destinationPassword);_x000D_
_x000D_
    PreparedStatement sourceStatement = srcConnection.prepareStatement("SELECT *  FROM src_table ");_x000D_
    ResultSet rs = sourceStatement.executeQuery();_x000D_
    rs.setFetchSize(1000); // not needed_x000D_
_x000D_
_x000D_
    ResultSetMetaData meta = rs.getMetaData();_x000D_
_x000D_
_x000D_
_x000D_
    List<String> columns = new ArrayList<>();_x000D_
    for (int i = 1; i <= meta.getColumnCount(); i++)_x000D_
        columns.add(meta.getColumnName(i));_x000D_
_x000D_
    try (PreparedStatement destStatement = destConnection.prepareStatement(_x000D_
            "INSERT INTO dest_table ("_x000D_
                    + columns.stream().collect(Collectors.joining(", "))_x000D_
                    + ") VALUES ("_x000D_
                    + columns.stream().map(c -> "?").collect(Collectors.joining(", "))_x000D_
                    + ")"_x000D_
            )_x000D_
    )_x000D_
    {_x000D_
        int count = 0;_x000D_
        while (rs.next()) {_x000D_
            for (int i = 1; i <= meta.getColumnCount(); i++) {_x000D_
                destStatement.setObject(i, rs.getObject(i));_x000D_
            }_x000D_
            _x000D_
            destStatement.addBatch();_x000D_
            count++;_x000D_
        }_x000D_
        destStatement.executeBatch(); // you will see all the rows in dest once this statement is executed_x000D_
        System.out.println("done " + count);_x000D_
_x000D_
    }

this can also be done like this if you don't want to use prepared statements.

String sql = "INSERT INTO course(course_code,course_desc,course_chair)"+"VALUES('"+course_code+"','"+course_desc+"','"+course_chair+"');"

Why it didnt insert value is because you were not providing values, but you were providing names of variables that you have used.