กริดใดมีรอบ 24 และมีไรเดอร์ของ Marco Melandri?ไม่จำเป็นต้องใช้โต๊ะทั้งหมด
Which Grid has Laps of 24, and a Rider of marco melandri?It is not neccessary to use all the tables.
 table_45956:  "Rider" [ text]  "Manufacturer" [ text]  "Laps" [ real]  "Time" [ text]  "Grid" [ real] 
SELECT SUM("Grid") FROM table_45956 WHERE "Laps" = '24' AND "Rider" = 'marco melandri'