title: Partially update table from csv
body: <p>I am running the following query:</p>
  
  <pre><code>CREATE TEMPORARY TABLE data LIKE customers;
  
  LOAD DATA INFILE 'D:/iban.csv'
  INTO TABLE data
  FIELDS TERMINATED BY ','
  (customers_id, customers_banktransfer_iban, customers_banktransfer_bic); 
  
  UPDATE data B
  INNER JOIN customers A USING (customers_id)
  SET A.customers_id = B.customers_id;
  SET A.customers_banktransfer_iban = B.customers_banktransfer_iban;
  SET A.customers_banktransfer_bic = B.customers_banktransfer_bic;
  DROP TEMPORARY TABLE data;
  </code></pre>
  
  <p>The error message I get is:</p>
  
  <pre><code>#1193 - Unknown system variable 'customers_banktransfer_iban' 
  </code></pre>
  
  <p>Anyone who knows what the problem is?</p>