title: Update table from another table and different database
body: <p>Basically, what I want to do is the following :
  I have a table 'users' in my first database (prc), like this :</p>
  
  <pre><code>prc.user :
  id_user : 45 | name_user : Test | login_user : test | pwd_user : test
  [...]
  </code></pre>
  
  <p>And in my second database (named : prc_test)   </p>
  
  <pre><code>prc_test.user
  id_user : 45 | name_user : Test | login_user : test | pwd_user : test
  [...]
  </code></pre>
  
  <p>The thing I want to do, is update all the "pwd_user" fields in "prc_test.user" with the values from pwd_user from "prc.user"
  But in the prc_test.user, the id are not the same as in prc.user, so I thought of doing it with the "name_user", (there are no doubles).</p>
  
  <p>Any clue in how I can do it ?
  I searched on Google, but what I found is always for some specific cases, or for insert statements...</p>
  
  <p>(I'm using MySQL5.5)</p>
  
  <p>Thanks !</p>