我在努力寻找每个国家数量最高和最低的经销商
见http://sqlfiddle.com/#!17/448f6/2
预期结果
"country" "min_qty_name" "max_qty_name"
1. "Madagascar" "Leonard Cardenas" "Gwendolyn Mccarty"
2. "Malaysia" "Arsenio Knowles" "Yael Carter"
3. "Palau" "Brittany Burris" "Clark Weaver"
4. "Tanzania" "Levi Douglas" "Levi Douglas"