To combine tables using UNION operator through a PHP program, we need to execute the SQL statement with UNION operator using the mysql2 function named query() as follows −

sql= " SELECT column_name(s) FROM table1 UNION SELECT column_name(s) FROM table2";
con.query(sql);

To combine tables using UNION operator through a PHP program, we need to execute the SQL statement with UNION operator using the JDBC type 4 driver function named executeQuery() as follows −

String sql = "SELECT column_name(s) FROM table1 UNION SELECT column_name(s) FROM table2";
statement.executeQuery(sql);

To combine tables using UNION operator through a PHP program, we need to execute the SQL statement with UNION operator using the MySQL Connector/Python function named execute() as follows −

union_query = "SELECT column_name(s) FROM table1 UNION SELECT column_name(s) FROM table2"
cursorObj.execute(union_query);

var mysql = require(''mysql2'');
var con = mysql.createConnection({
    host: "localhost",
    user: "root",
    password: "Nr5a0204@123"
});

  //Connecting to MySQL
  con.connect(function (err) {
  if (err) throw err;
  console.log("Connected!");
  console.log("--------------------------");

  //Creating a Database
  sql = "create database TUTORIALS"
  con.query(sql);

  //Select database
  sql = "USE TUTORIALS"
  con.query(sql);

  //Creating PROSPECT table
  sql = "CREATE TABLE PROSPECT( fname varchar(400), lname varchar(400), addr varchar(200));"
  con.query(sql);

  //Inserting Records
  sql = "INSERT INTO PROSPECT (fname, lname, addr) VALUES (''peter'', ''Jones'', ''482 Rush St., Apt. 402''), (''Bernice'', ''Smith'', ''916 Maple Dr.'');"
  con.query(sql);

  //Creating CUSTOMER table
  sql = "CREATE TABLE CUSTOMER( last_name varchar(400), first_name varchar(400), address varchar(200));"
  con.query(sql);
  
  //Inserting Records
  sql = "INSERT INTO CUSTOMER (last_name, first_name, address) VALUES (''Peterson'', ''Grace'', ''16055 Seminole Ave.''), (''Smith'', ''Bernice'', ''916 Maple Dr.''), (''Brown'', ''Walter'', ''8602 1st St.'');"
  con.query(sql);

  //Creating vendor table
  sql = "CREATE TABLE vendor( company varchar(400), street varchar(400));"
  con.query(sql);

  //Inserting Records
  sql = "INSERT INTO vendor (company, street) VALUES (''ReddyParts, Inc.'', ''38 Industrial Blvd.''), (''Parts-to-go, Ltd.'', ''213B Commerce Park.'');"
  con.query(sql);

  //Using UNION
  sql = "SELECT fname, lname, addr FROM prospect UNION SELECT first_name, last_name, address FROM customer UNION SELECT company, '''', street FROM vendor;"
  con.query(sql, function(err, result){
    if (err) throw err
    console.log(result)
  });
});   

Output

The output produced is as follows −

Connected!
--------------------------
[
  { fname: ''peter'', lname: ''Jones'', addr: ''482 Rush St., Apt. 402'' },
  { fname: ''Bernice'', lname: ''Smith'', addr: ''916 Maple Dr.'' },
  { fname: ''Grace'', lname: ''Peterson'', addr: ''16055 Seminole Ave.'' },
  { fname: ''Walter'', lname: ''Brown'', addr: ''8602 1st St.'' },
  { fname: ''ReddyParts, Inc.'', lname: '''', addr: ''38 Industrial Blvd.'' },
  { fname: ''Parts-to-go, Ltd.'', lname: '''', addr: ''213B Commerce Park.'' }
]    

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class UnionOperator {
    public static void main(String[] args) {
        String url = "jdbc:mysql://localhost:3306/TUTORIALS";
        String user = "root";
        String password = "password";
        ResultSet rs;
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            Connection con = DriverManager.getConnection(url, user, password);
            Statement st = con.createStatement();
            //System.out.println("Database connected successfully...!");
            String sql = "SELECT fname, lname, addr FROM prospect UNION SELECT first_name, last_name, address FROM customer UNION SELECT company, '''', street FROM vendor";
            rs = st.executeQuery(sql);
            System.out.println("Table records: ");
            while(rs.next()) {
                String fname = rs.getString("fname");
                String lname = rs.getString("lname");
                String addr = rs.getString("addr");
                System.out.println("First Name: " + fname + ", Last Name: " + lname + ", Address: " + addr);
            }
        }catch(Exception e) {
            e.printStackTrace();
        }
    }
}                      

Output

The output obtained is as shown below −

Table records: 
First Name: Peter, Last Name: Jones, Address: 482 Rush St., Apt. 402
First Name: Bernice, Last Name: Smith, Address: 916 Maple Dr.
First Name: Grace, Last Name: Peterson, Address: 16055 Seminole Ave.
First Name: Walter, Last Name: Brown, Address: 8602 1st St.
First Name: ReddyParts, Inc., Last Name: , Address: 38 Industrial Blvd.
First Name: Parts-to-go, Ltd., Last Name: , Address: 213B Commerce Park.        

import mysql.connector
#establishing the connection
connection = mysql.connector.connect(
    host=''localhost'',
    user=''root'',
    password=''password'',
    database=''tut''
)
cursorObj = connection.cursor()
union_query = f"""
SELECT fname, lname, addr FROM prospect
    UNION
    SELECT first_name, last_name, address FROM customer
    UNION
    SELECT company, '''', street FROM vendor;
"""
cursorObj.execute(union_query)
# Fetching all the rows that meet the criteria
filtered_rows = cursorObj.fetchall()
for row in filtered_rows:
    print(row)
cursorObj.close()
connection.close()                      

Output

Following is the output of the above code −

(''Peter'', ''Jones'', ''482 Rush St., Apt. 402'')
(''Bernice'', ''Smith'', ''916 Maple Dr.'')
(''Grace'', ''Peterson'', ''16055 Seminole Ave.'')
(''Walter'', ''Brown'', ''8602 1st St.'')
(''ReddyParts, Inc.'', '''', ''38 Industrial Blvd.'')
(''Parts-to-go, Ltd.'', '''', ''213B Commerce Park.'')