title: how to avoid empty entries in sql?
body: <pre><code>CREATE TABLE emp3(
     id int(3) auto_increment,
     first_name varchar(30) NOT NULL,
     last_name varchar(30), 
     email varchar(20) not null unique,
     PRIMARY KEY (id)
  ) 
  </code></pre>
  
  <p>This is my table.
  if i insert query like this insert into emp3   values(3,' ','',''); it is getting stored in the table.
  but i should avoid this.How can i do it?</p>