单项选择题

What is the candidate key of a relational database

A．A field with a constraint placed on it.
B．A set of fields that have no data in them.
C．A set of fields in a table used to identify a record uniquely.
D．Fields from multiple tables that are used for sorting records.

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单项选择题

The following sectors are requested from the disk:11,1,36,16,34,9,12What is the order of the sector reads if you are using the elevator algorithm

A．1,9,11,12,16,34,36
B．11,1,36,16,34,9,12
C．11,12,9,16,1,34,36
D．11,12,16,34,36,9,1

单项选择题

What state is a process in when it can t run because it needs a resource to become available

A．Ready
B．Interrupt
C．Blocked
D．Running