title: MYSQL Group_Concat values into one field but keep multiple rows
body: <p>I have two tables in MySQL, one containing a single value in each row and the other containing the same values, but they are all combined into a single row. So for example:</p>
  
  <p>Table1:</p>
  
  <pre><code>Column1
  a
  b
  </code></pre>
  
  <p>Table2:</p>
  
  <pre><code>Column1
  a,b
  </code></pre>
  
  <p>I would like to make a mapping table based off of table 1 so that I can do a join on them.  The result I am looking for would be this:</p>
  
  <pre><code>Column1 |  Column2
  a       |  a,b
  b       |  a,b
  </code></pre>
  
  <p>I have tried this:</p>
  
  <pre><code>SELECT Column1, GROUP_CONCAT(DISTINCT Column1) AS Column2 
  FROM Table1
  </code></pre>
  
  <p>But it just returns a single row:</p>
  
  <pre><code>Column1 | Column2
  a       | a,b
  </code></pre>
  
  <p>I have also tried adding a group by clause:</p>
  
  <pre><code>SELECT Column1, GROUP_CONCAT(DISTINCT Column1) AS Column2 
  FROM Table1
  GROUP BY Column1
  </code></pre>
  
  <p>This returns each row, but doesn't concatenate the fields into column2:</p>
  
  <pre><code>Column1 | Column2
  a       | a
  b       | b
  </code></pre>
  
  <p>Is there any way to solve this?  I appreciate the help!</p>