title: Faster way to update 250k rows with SQL
body: <p>I need to update about 250k rows on a table and each field to update will have a different value depending on the row itself (not calculated based on the row id or the key but externally).</p>
  
  <p>I tried with a parametrized query but it turns out to be slow (I still can try with a table-value parameter, SqlDbType.Structured, in SQL Server 2008, but I'd like to have a general way to do it on several databases including MySql, Oracle and Firebird).</p>
  
  <p>Making a huge concat of individual updates is also slow (BUT about 2 times faster than making thousands of individual calls (roundtrips!) using parametrized queries)</p>
  
  <p>What about creating a temp table and running an update joining my table and the tmp one? Will it work faster?</p>