Piwik supports only mysql, I want to integrate with sql server. Is there any way to migrate from mysql to sql server.
You've already answered the question, Piwik only supports MySQL, at least for now.
However, there is the possibility of pointing it to a another database server (MS SQL) with a different port and database driver. but since SQL differs between MySQL and MS SQL, so you might get unexpected results (or errors because you use some feature of MySQL that MS SQL doesn't support). You also need a different driver that Piwik would have to support.
You can get some more info on Piwik forum about MS SQL.