MySQL Update example Using group by and Inner Join

	 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;