I like the comma in front for SQL better than at the end but you still have the problem of one of the fields missing a comma, the first field instead of the last but I guess maybe you're more likely to move fields and forget to add/remove a comma at the end.

Who writes trailing commas in sql?In every company I worked with the standard was prefix commas:

<pre><code> var , var2 , var3 , var4 </code></pre>

I recommend writing a function to remove trailing commas from SQL. Big time save.