There are following business statements for an information system:①A customer submit 0 or more orders;②An order can only be submitted by one customer. There are two classes in the system “Customer” and “Order”. For each instance of Order Class, there are ____ instance(s) of Customer Class; while for each instance of Customer Class, there are ____ instance(s) of Order Class.
A: (1) 1 (2) 1
B: (1) 1 (2) 1 or more
C: (1) 1 (2) 0 or more
D: (1) 0 or more (2) 1
A: (1) 1 (2) 1
B: (1) 1 (2) 1 or more
C: (1) 1 (2) 0 or more
D: (1) 0 or more (2) 1
举一反三
- Which of the following is the order of applying object-oriented concept in programming A: instance creating — class defining — use attributes or methods through the instance B: class defining — instance creating — use attributes or methods through the instance C: instance creating — use attributes or methods through the instance — class defining D: class defining — use attributes or methods through the instance —instance creating
- 哪种方式通过对比页面变化能判断 sql 注入()。 A: order 1 和 order 2 B: ' or 1=1 和' or 1=2 C: '和'' D: ' and 1=1 和' and 1=2
- There are ______ many League members in Class 1 ______ in Class 2. A: more, than B: as, as C: so, as
- 设两个向量组α1,α2,...,αs和β1,β2,...,βs均线性相关,则() A: 有不全为0的数λ1,λ2,…,λs使λ1α1+λ2α2+…+λsαs=0和λ1β1+λ2β2+…λsβs=0 B: 有不全为0的数λ1,λ2,…,λs使λ1(α1+β1)+λ2(α2+β2)+…+λs(αs+βs)=0 C: 有不全为0的数λ1,λ2,…,λs使λ1(α1-β1)+λ2(α2-β2)+…+λs(αs-βs)=0 D: 有不全为0的数λ1,λ2,…,λs和不全为0的数μ1,μ2,…,μs使λ1α1+λ2α2+…+λsαs=0和μ1β1+μ2β2+…+μsβs=0
- The number of subgroups of order 25 of an Abelian group of order 50 is ( ). A: 0 B: 1 C: 2 D: 3