查询以获取订单小于先前订单的客户列表(Query to get list of customers whose orders are less than the previous order)

 我正在尝试编写一个sql来获取客户列表，其总订购单位始终小于之前的订单。 如在第n顺序中的总数量小于第n-1阶的总数量等 
 
 SQL创建和填充表 
 
create table orders (order_id int, customer_id varchar(5), order_date date, product_id varchar(5), quantity int);

Insert into orders values(01,'C1','2000-01-01','P1',10);
Insert into orders values(02,'C2','2002-01-01','P2',15);
Insert into orders values(03,'C3','2002-04-01','P3',17);
Insert into orders values(04,'C4','2003-04-01','P1',20);
Insert into orders values(05,'C4','2006-01-01','P2',1);
Insert into orders values(06,'C1','2006-05-01','P5',7);
 
 我假设我需要根据Order_id序列号编写一个过程和LOOP。 一旦进入循环，我需要选择对应于order_id的product_id和数量Q. 然后检查是否对于相同的order_id，是否有任何其他数量Q1小于Q.如果是，则打印customer_id。 如果没有，则order_id移动到下一个order_id。 
 
 我不确定如何实现我检查数量列的部分，以检查订单是否还有其他数量Q1 <Q for order_id？ 
 
 请澄清 

I am trying to write a sql to get the list of customers whose total ordered units is consistently lesser than the previous order. As in Total Qty in nth order is less than Total qty in n-1 th order, etc
 
SQL to create and populate table
 
create table orders (order_id int, customer_id varchar(5), order_date date, product_id varchar(5), quantity int);

Insert into orders values(01,'C1','2000-01-01','P1',10);
Insert into orders values(02,'C2','2002-01-01','P2',15);
Insert into orders values(03,'C3','2002-04-01','P3',17);
Insert into orders values(04,'C4','2003-04-01','P1',20);
Insert into orders values(05,'C4','2006-01-01','P2',1);
Insert into orders values(06,'C1','2006-05-01','P5',7);
 
I am assuming that I need to write a procedure and LOOP based on Order_id serial number. Once in loop, I need to pick the product_id and quantity Q corresponding to order_id. Then check whether for the same order_id there is any other quantity Q1 that is less than Q. If so, then I print the customer_id. If not, then the order_id moves to next order_id.
 
I am not sure how to implement the part where I check the quantity column to check whether there is any other quantity Q1 < Q for order_id?
 
Please clarify 

原文：https://stackoverflow.com/questions/40009984