单项选择题

The most commonly used locked level in implementing concurrency control is at which of the following levels ( )

A．record
B．database
C．table
D．field

<上一题目录下一题>

热门试题

单项选择题

In the following statements about functional dependency, which one is incorrect ( )

X, then X→X'
B．if X→Y and Y’

Y, then X→Y'
C．if X→Y and X’

X, then X'→Y
D．if X→Y and Y→Z, then X→Z

单项选择题

下面命题的判断正确的是( )。 Ⅰ．完全图Kn(n≥1)都是哈密尔顿图 Ⅱ．完全二部图Kn,m(n≥1，m≥1)都是欧拉图 Ⅲ．任何平面图G的对偶图G*的对偶图G**与G同构

A．只有Ⅰ和Ⅱ为真
B．只有Ⅲ为真
C．只有Ⅱ为假
D．全为假

相关试题