รอบเฉลี่ยของ andrea de cesaris คือเท่าใด?ไม่จำเป็นต้องใช้ตารางทั้งหมด
What is the average Laps for andrea de cesaris?It is not neccessary to use all the tables.
 table_55851:  "Driver" [ text]  "Constructor" [ text]  "Laps" [ real]  "Time/Retired" [ text]  "Grid" [ real] 
SELECT AVG("Laps") FROM table_55851 WHERE "Driver" = 'andrea de cesaris'