title: compare two table values
body: <p>I have 2 tables table A and table B. In table B we have to check if all the column entered is exactly as in table A, means if a row exists in table B then the same row will be there in table A too. also table A may have rows which are not in table B. if there is a row which is not in table A and is there in table B, an alert should be displayed showing which element is extra in table B. 
  Can we do this using join? if so what will be the sql code? </p>