title: SQL Query - Ensure a row exists for each value in ()
body: <p>Currently struggling with finding a way to validate 2 tables (efficiently lots of rows for Table A) </p>
  
  <p>I have two tables</p>
  
  <p><strong>Table A</strong> <br></p>
  
  <pre><code> ID 
   A
   B 
   C
  </code></pre>
  
  <p><strong>Table matched</strong></p>
  
  <pre><code>ID Number
  A   1
  A   2
  A   9
  B   1
  B   9
  C   2
  </code></pre>
  
  <p>I am trying to write a SQL Server query that basically checks to make sure for every value in Table A there exists a row for a variable set of values ( 1, 2,9) </p>
  
  <p>The example above is incorrect because t should have for every record in A a corresponding record in Table matched for each value (1,2,9).  The end goal is:</p>
  
  <p><strong>Table matched</strong></p>
  
  <pre><code>ID Number
  A   1
  A   2
  A   9
  B   1
  B   2
  B   9
  C   1
  C   2
  C   9
  </code></pre>
  
  <p>I know its confusing, but in general for every X in ( some set ) there should be a corresponding record in Table matched.  I have obviously simplified things.</p>
  
  <p>Please let me know if you all need clarification.</p>