title: Update column on basis of comma separated field comparison
body: <p>I have a table Client with columns ClientID, Name</p>
  
  <pre><code>ClientID|Name
  1       |A
  2       |B
  3       |C
  4       |D
  5       |E
  </code></pre>
  
  <hr>
  
  <p>A Users table with columns : UserID ,AllowedClients, DeniedClients</p>
  
  <pre><code>USERID |AllowedClients|DeniedClients
  U1     |1,2,5         |NULL
  U2     |2,1           |NULL
  U3     |1,4,5         |NULL
  U4     |5,1,3         |NULL
  U5     |2,3           |NULL
  </code></pre>
  
  <p>Currently all DeniedClients are set to NULL.</p>
  
  <p>I need to update The Users table,
  something like : </p>
  
  <pre><code>Update users set DeniedClients= (All existing ClientIDs in Client table) –` (users.AllowedClients)
  </code></pre>
  
  <hr>
  
  <p>OutPut:</p>
  
  <pre><code>USERID |AllowedClients|DeniedClients
  U1     |1,2,5         |3,4
  U2     |2,1           |3,4,5
  U3     |1,4,5         |2,3
  U4     |5,1,3         |2,4
  U5     |2,3           |1,4,5
  </code></pre>
  
  <p>How to write this query without using cursor.</p>