title: How to look up one column to return a column I need to the join tables all in one mysql call
body: <p>I'm making a simple blog as a learning excercise. Here are two tables I have but simplified. </p>
  
  <p>Table <code>Users</code> contains columns <code>"id"</code> and <code>"url"</code> </p>
  
  <p>Table <code>Entries</code> contains column <code>"user_id"</code></p>
  
  <p>I have the url of the user and I want to get all the entries for that user. I know how I can do this with two mysql calls. First I would use the url to get the id, then in another call use the id to get the entries. </p>
  
  <p>I know how I could join the tables once I have the id. But I don't know how I can join the tables with the url before I have the id.</p>
  
  <p>This is probably pretty obvious, but I've been reading up on table joins all day and not seen an example that covers what I'm trying to do, and not sure how to word it to get results from google. </p>