title: How to find valid combinations in a table using Oracle SQL
body: <p>I have 2 tables.</p>
  
  <p>One is Admin Table with all valid combinations and other is a Transaction table with the transactions.</p>
  
  <p>I am trying to write a query which will give me the result of invalid combinations from transaction table.</p>
  
  <p>The query should return the invalid transactions. </p>
  
  <p>As you can see in the example below ABCD - TUV and IJKL - EFG are not valid combinations. </p>
  
  <p>Admin Table</p>
  
  <pre><code>Column A    Column B
  ABCD        XYZ
  ABCD        EFG
  EFGH        XYZ
  IJKL        TUV
  IJKL        XYZ
  </code></pre>