What is the first step the use in detecting data type mismatch errors?

JavaScript

Better if you use JavaScript or another scripting language to analyse what is sent to the server in the first place. Most of the browsers support JavaScript.

Suppose there is an input type of text of the simple html form

MySQL

Name:

Age :

// The button below makes sure that client side validation is done otherwise it doesn't send data to servers

// Here the "return checkData()" forces the client-side validation to occur before sending it to server

// The neat little code tells if JavaScript is enabled/disabled in browser

Most of things would be easy this way but alas things aren't so easy. You also need to validate data on the server side using echo statements & control loops before finally posting data in MySQL table