Hello, I hope you are doing well.
This is a though question to answer, because it really depends on your project requirements. In summary:

1. First, you need to start by learning a bit about SQL and learn how to setup a table with all the fields that you want to store in your database.
2. Then, you need to write a PHP script that will receive the data and insert it into your database
3. Your ESP will send the data to your PHP script based on the defined parameters

I hope this helps!
Rui

Hullo Rui and thank you for the time to respond.
I am fine setting up the tables and structure in SQL – it is getting the information into them that i struggle with.
I am sure it cant be too hard but havent found the right website to get me there yet.
As a simple example  let us say table 1 has three variables with a times stamp and table 2 has another three variables with a time stamp.
var1, var2, var3 for table 1 
var4, var5, var6 for table 2.
var’s 1-6 are read from the one device.
 how do i export those variables from the device (one long string?) and get them in to the correct table thru PHP. 
 Any pointers appreciated.

It’s a bit hard to explain in a few sentences, learning PHP is a full course on itself, but I highly recommend this website:

• http://www.w3schools.com/php/default.asp

I have this sample project about PHP and MySQL: ESP32/ESP8266 Insert Data into MySQL Database using PHP and Arduino IDE
This script receives the readings from the ESP and inserts them in the database.

• https://raw.githubusercontent.com/RuiSantosdotme/ESP32-ESP8266-PHP-MySQL/master/code/post-esp-data.php

if ($_SERVER["REQUEST_METHOD"] == "POST") {
 $api_key = test_input($_POST["api_key"]);
 if($api_key == $api_key_value) {
  $sensor = test_input($_POST["sensor"]);
  $location = test_input($_POST["location"]);
  $value1 = test_input($_POST["value1"]);
  $value2 = test_input($_POST["value2"]);
  $value3 = test_input($_POST["value3"]);

  $sql = "INSERT INTO SensorData (sensor, location, value1, value2, value3)
VALUES ('" . $sensor . "', '" . $location . "', '" . $value1 . "', '" . $value2 . "', '" . $value3 . "')";
You could receive it like this:
$var1= test_input($_POST["var1"]);
$var2= test_input($_POST["var2"]);
$var3= test_input($_POST["var3"]);
$sql = "INSERT INTO table1 (var1, var2, var3) VALUES ('" . $var1 . "', '" . $var2 . "', '" . $var3 . "')";
It would be something like that… Then your ESP would make an HTTP POST request with var1, var2, var3 variables in the request.

• https://raw.githubusercontent.com/RuiSantosdotme/ESP32-ESP8266-PHP-MySQL/master/code/ESP32_ESP8266_MySQL_Database_PHP.ino

Or you can learn more about HTTP: ESP32 HTTP GET and HTTP POST with Arduino IDE (JSON, URL Encoded, Text) https://randomnerdtutorials.com/esp32-http-get-post-arduino/

Dear Rui
Thank you for your patience – I have followed that example previously with many experimental permutations (it works fine for one table). I have tried modifying it by the addition of another “insert” into a different table with / without an additional loop but I cannot get that to work. Some investigation suggests that it wont and I need to do a transaction using BEGIN…INSERT… COMMIT I have tried this as well without success. Other investigation suggest that just good PHP programming will do it without the need for a transaction.?? I do understand the concepts but struggle with the programming for what i understand should be a relatively common event.
 Kind regards

But did you create a new table in your database? Is it created?
If it is, you need to insert data in your new table.