soql The inner and outer selects should not be on the same object type code example

Example 1: get all the child of the same class javascript

var doc = document.getElementById("test");
var notes = null;
for (var i = 0; i < doc.childNodes.length; i++) {
    if (doc.childNodes[i].className == "4") {
      notes = doc.childNodes[i];
      break;
    }        
}

Example 2: Use multiple conditional operators in the checkSign function to check if a number is positive, negative or zero. The function should return "positive", "negative" or "zero".

function checkSign(num) {
  return (num > 0) ? 'positive' : (num < 0) ? 'negative' : 'zero';
}