title: Update columns when value is numeric in tsql
body: <p>I want to normalize date fields from an old badly designed db dump. I now need to update every row, where the datefield only contains the year.</p>
  
  <pre><code>update table set date = '01.01.' + date
  where date like '____' and isnumeric(date) = 1 and date &gt;= 1950
  </code></pre>
  
  <p>But this will not work, because sql does not do short circuit evaluation of boolean expressions. Thus I get an error "error converting nvarchar '01.07.1989' to int"</p>
  
  <p>Is there a way to work around this? The column also contains strings with a length of 4, which are not numbers (<code>????</code>, <code>5/96</code>, <code>70/8</code>, etc.) the table <em>only</em> has 60000 rows</p>