title: Insert two columns from different tables into one table
body: <p>I have two tables, one with user-ids and another with item-ids. There are repeated entries in both tables but that is required. There are 42,000 entries in both tables.</p>
  
  <p>I need to merge these tables such that there are 42,000 entries in the third table "user-item" such that first column contains the user-ids and second column contains item-ids as is from the two previous tables.</p>
  
  <blockquote>
    <p>Userinfo table: (column is userid)</p>
  </blockquote>
  
  <p>18974</p>
  
  <p>41092</p>
  
  <p>4287</p>
  
  <p>41092 and so on</p>
  
  <blockquote>
    <p>Iteminfo table: (column is itemid)</p>
  </blockquote>
  
  <p>13</p>
  
  <p>182</p>
  
  <p>13</p>
  
  <p>76 and so on</p>
  
  <blockquote>
    <p>Required table:</p>
  </blockquote>
  
  <p>Userid  | Itemid</p>
  
  <p>18974   | 13</p>
  
  <p>41092   | 182</p>
  
  <p>4287    |  13</p>
  
  <p>41092   | 76</p>
  
  <p>and so on.</p>