3 里程碑
    
    一个流程有三个步骤 现在需要把各个步骤的时间填到报表之中。
    
    SERVICESSCHEDULE
    SHOP_ID               CHAR(3)       商铺号
    ORDER_NBR        CHAR(10)     订单号
    SCH_SEQ             INTEGER       步骤
    SERVICE_TYPE   CHAR(2)        服务类型
    SCH_DATE            DATE            实施时间
    
    (1 = 'processed')
    (2 = 'completed')
    (3 = 'confirmed')
    CASE子句的使用
    SERVICESSCHEDULE

SHOP_ID    ORDER_NBR    SCH_SEQ    SERVICE_TYPE    SCH_DATE
2      4155526710    1    1     1994-7-16
2      4155526710    2    1     1994-7-30
2      4155526710    3    1     1994-10-1
2      4155526711    1    1     1994-7-16
2      4155526711    2    1     1994-7-30
2      4155526711    3    1    

使用单条语句完成上述功能

数据如下

create table PRINTERCONTROL
(
  USER_ID             CHAR(10),
  PRINTER_NAME        CHAR(4) not null,
  PRINTER_DESCRIPTION CHAR(40) not null
)
;
alter table PRINTERCONTROL
  add primary key (PRINTER_NAME);


insert into PRINTERCONTROL (USER_ID, PRINTER_NAME, PRINTER_DESCRIPTION)
values ('chacha    ', 'LPT1', 'First floor_printer                     ');
insert into PRINTERCONTROL (USER_ID, PRINTER_NAME, PRINTER_DESCRIPTION)
values ('lee       ', 'LPT2', 'Second floor_printer                    ');
insert into PRINTERCONTROL (USER_ID, PRINTER_NAME, PRINTER_DESCRIPTION)
values ('thomas    ', 'LPT3', 'Third floor_printer                     ');
insert into PRINTERCONTROL (USER_ID, PRINTER_NAME, PRINTER_DESCRIPTION)
values (null, 'LPT4', 'Common printer for new user             ');
insert into PRINTERCONTROL (USER_ID, PRINTER_NAME, PRINTER_DESCRIPTION)
values (null, 'LPT5', 'Common printer for new user             ');
commit;