title: What should i include to prevent the popup error shown in MYSQL?
body: <p><img src="https://i.stack.imgur.com/tRzLA.png" alt="enter image description here"></p>
  
  <p>I have created these 4 boxes description. If I didn't key in anything for all the boxes, an error message will appear. However, I want an additional function where if I only key in information for the arm (arm exercise and no. of times), I still can submit. </p>
  
  <p>I created an if else function but it shows an error when I key in only the first two box and the other two boxes are blank.</p>
  
  <blockquote>
    <p>For input string : " "</p>
  </blockquote>
  
  <p>this is my string sql.</p>
  
  <blockquote>
    <p>String sql="Insert into exercise(Arm, Time1, Leg, Time2)
    Values(?,?,?,?)";</p>
  </blockquote>
  
  <p>edited:
  <a href="https://i.stack.imgur.com/tRzLA.png" rel="nofollow noreferrer">enter image description here</a></p>