Defenseload

 UPDATE tmpbilledsummary AS a 
 INNER JOIN
 ( SELECT
 a.practiceCode AS accountCode, b.name AS accountName, COUNT(*) AS counter
 FROM 
 laborder a, practice b
 WHERE 
 a.practiceCode = b.code 
 AND
 a.DOS >= COALESCE(pFromDOS,DOS)
 AND 
 a.DOS <= COALESCE(pToDOS,DOS)
 GROUP BY a.practiceCode
 ) AS b
 ON 
 a.accountCode = b.accountCode 
 SET a.clientOrders = b.counter;