- 在sql_invoicing库invoices表中按不同顾客分组统计下半年总销售额并降序排列
- 在sql_invoicing库invoices表算各州各城市的总销售额
下面的数据依次是：
invoice_id, number, client_id, invoice_total, payment_total, invoice_date, due_date, payment_date
'1', '91-953-3396', '2', '101.79', '0.00', '2019-03-09', '2019-03-29', NULL
'2', '03-898-6735', '5', '175.32', '8.18', '2019-06-11', '2019-07-01', '2019-02-12'
'3', '20-228-0335', '5', '147.99', '0.00', '2019-07-31', '2019-08-20', NULL
'4', '56-934-0748', '3', '152.21', '0.00', '2019-03-08', '2019-03-28', NULL
'5', '87-052-3121', '5', '169.36', '0.00', '2019-07-18', '2019-08-07', NULL
'6', '75-587-6626', '1', '157.78', '74.55', '2019-01-29', '2019-02-18', '2019-01-03'
'7', '68-093-9863', '3', '133.87', '0.00', '2019-09-04', '2019-09-24', NULL
'8', '78-145-1093', '1', '189.12', '0.00', '2019-05-20', '2019-06-09', NULL
'9', '77-593-0081', '5', '172.17', '0.00', '2019-07-09', '2019-07-29', NULL
'10', '48-266-1517', '1', '159.50', '0.00', '2019-06-30', '2019-07-20', NULL
'11', '20-848-0181', '3', '126.15', '0.03', '2019-01-07', '2019-01-27', '2019-01-11'
'13', '41-666-1035', '5', '135.01', '87.44', '2019-06-25', '2019-07-15', '2019-01-26'
'15', '55-105-9605', '3', '167.29', '80.31', '2019-11-25', '2019-12-15', '2019-01-15'
'16', '10-451-8824', '1', '162.02', '0.00', '2019-03-30', '2019-04-19', NULL
'17', '33-615-4694', '3', '126.38', '68.10', '2019-07-30', '2019-08-19', '2019-01-15'
'18', '52-269-9803', '5', '180.17', '42.77', '2019-05-23', '2019-06-12', '2019-01-08'
'19', '83-559-4105', '1', '134.47', '0.00', '2019-11-23', '2019-12-13', NULL
