title: MySQL efficient querying
body: <p>I am fairly new to MySQL. Considering this table:</p>
  
  <pre><code> ID INT(11) UNSIGNED NOT NULL AUTO_INCREMENT,
    User_name VARCHAR(35) NOT NULL,
    Full_name VARCHAR(55) NOT NULL,
    User_vars VARCHAR(255) NOT NULL,
    BirthDay DATE NOT NULL,
    password CHAR(70) NOT NULL,  
    Security_hint VARCHAR(27) NOT NULL,
    Email VARCHAR(225) NOT NULL,
    userType ENUM ('a','b','c','d') NOT NULL DEFAULT 'a',
    Signup_Date TIMESTAMP NOT NULL  DEFAULT CURRENT_TIMESTAMP,
    activation   TINYINT(1) UNSIGNED NOT NULL,
    Ip BINARY(16) NOT NULL,
    PRIMARY KEY (ID),
    UNIQUE KEY User_name (User_name,Email)
  </code></pre>
  
  <p>I am using the following queries to check whether an email or user name exists in this table:</p>
  
  <pre><code>    $query1 ="SELECT id FROM signup WHERE Email='$Email_Input' LIMIT 1";            
  $result1 = mysql_query($query1) 
  
  $query2 = "SELECT id FROM signup WHERE User_name='$User_name' LIMIT 1";         
  $result2 = mysql_query($query2);
  
  if (mysql_num_rows($result2)&gt;0){    
  echo '1';
  }
  else if (mysql_num_rows($result1)&gt;0){   
  
  echo '1';
  }
  </code></pre>
  
  <p>My question: Is there an efficient way to issue just one query to check the existence of both?</p>