条码是实现()的技术基础。
A.GIS
B.POS系统
C.EDI
D.电子商务
E.供应链管理
参考答案:B, C, D, E
解析:本题考查条码技术。参见教材p117
查询订购单号(字符型,长度为4)尾字符是“1”的错误命令是
A.SELECT*FROM订单WHERE SUBSTR(订购单号,4)=“1”
B.SELECT*FROM订单WHERE SUBSTR(订购单号,4,1)=“1”
C.SELECT*FROM订单WHERE“1”$订购单号
D.SELECT*FROM订单WHERE RIGHT(订购单号,1)=“1”
It was about 600 years ago ______the first clock with a face and an hour hand was made. [ ]
A. that
B. until
C. before
D. when