title: How to copy one column of a table into another table's column in PostgreSQL comparing same ID
body: <p>I need to copy ref_id1 from table1 TO the column ref_id2 in the table2 the two things matching will be : id (same column name), a_ref1 &amp; b_ref1 (column names are different but numerical value will be identical).</p>
  
  <p>Table1</p>
  
  <pre><code>ID      ref_id1                     a_ref1
  9     2.3456762498;               1367602349
  9     1.61680784158;              1367653785
  9     2.63461385408;              1367687746
  9     0;                          1367688520
  9     0.780442217152;             1367740313
  9     3.18328461662;              1367773889
  9     0.775471247616;             1367774978
  </code></pre>
  
  <p>Table2</p>
  
  <pre><code>ID          b_ref1                      ref_id2
  9        1367602349;
  9        1367740313;
  9        1367774978;
  2        1357110511;
  2        1357186899;
  2        1357195928;
  2        1357199525;
  </code></pre>
  
  <p>In a nutshell need to copy ref_id1 to ref_id2 by comparing id and a_ref1 with b_ref1, Please let me know how to do that.</p>