Gregg Mettler เขียนไว้กี่ตอน?ไม่จำเป็นต้องใช้ตารางทั้งหมด
How many episodes were written by Gregg Mettler?It is not neccessary to use all the tables.
 table_29436238_1:  (no_in_series [ VARCHAR ] written_by [ VARCHAR) ]
SELECT COUNT(no_in_series) FROM table_29436238_1 WHERE written_by = "Gregg Mettler"