title: Insert normalized comma-separated field into a new table
body: <p>In MySQL I have a <code>catalog</code> table like this:</p>
  <pre><code>id | name  | products |
  ---|-------|----------|
   5 | name5 |    1,2,3 |
   6 | name6 |      2,3 |
   7 | name7 |        3 |
  </code></pre>
  <p>And a <code>product</code> table like this:</p>
  <pre><code>id | name  |
  ---|-------|
   1 | name1 |
   2 | name2 |
   3 | name3 |
  </code></pre>
  <p>Since data retrieving with <code>FIND_IN_SET</code> with a join is quite slow I created new table called <code>catalog_product</code> (catalog_id, product_id).</p>
  <p>Is there a way to <strong>insert the records into the new table</strong> with one query? This is the desired result:</p>
  <pre><code>catalog_id | catalog_id |
  ------------------------|
           5 |          1 |
           5 |          2 |
           5 |          3 |
           6 |          2 |
           6 |          3 |
           7 |          3 |
  </code></pre>
  <p>MySQL version: <code>mysql  Ver 14.14 Distrib 5.7.33, for Linux (x86_64) using  EditLine wrapper</code></p>