数据库中有一个表名为“Order”的表，结构和数据如下：
请你按照下面要求写出sql语句
1.统计出每个地区的合同金额合计并按此倒序排列显示。
SELECT region,a.COUNT FROM (SELECT region,SUM(total) AS COUNT
FROM OrderTest GROUP BY region) a ORDER BY a.COUNT DESC;
2.统计出每个地区销售人员数量
SELECT region,COUNT(*) FROM ordertest GROUP BY region;
3.统计出每个地区合同金额最少的销售人员
SELECT e.* FROM ordertest e,
(SELECT MIN(total) minsales,sales ,region FROM ordertest
GROUP BY region) a
WHERE e.region = a.region
AND e.total =a.minsales;
4.统计出所有超过本地区合同金额平均值得合同及金额
内连接
SELECT e.* FROM ordertest e
JOIN (SELECT AVG(total) minsales,sales ,region FROM ordertest
GROUP BY region) a
ON e.region = a.region
AND e.total >a.minsales;
外连接
SELECT e.* FROM ordertest e
LEFT OUTER JOIN (SELECT AVG(total) minsales,sales ,region FROM ordertest
GROUP BY region) a
ON e.region = a.region
WHERE e.total >a.minsales;