题目
题目

ECON3310001.1251 Quiz 5: Introduction to Database Management Systems

单项选择题

Number Owner Balance Type 101 John Smith 1000.00 checking 102 Werner Wei 2000.00 checking 103 John Smith 1000.00 savings 104 Muhammad Jones 1000.00 checking 105 Hugh Martin 10,000.00 checking   What is the result of the following query for the relation Account? SELECT DISTINCT Owner FROM Account Note that we are representing the result as a set {...} of tuples (...), with each attribute explicitly listed along with its value.

选项
A.{(Owner: “John Smith”), (Owner: “Werner Wei”), (Owner: “Muhammad Jones”), (Owner: “Hugh Martin”)}
B.{(Number: 101, Owner: “J. Smith”), (Number: 102, Owner: “W. Wei”), (Number: 103, Owner: “J. Smith”), (Number: 104, Owner: “M. Jones”), (Number: 105, Owner: “H. Martin”)}
C.{(Number: 101, Owner: “John Smith”), (Number: 102, Owner: “Werner Wei”), (Number: 103, Owner: “John Smith”), (Number: 104, Owner: “Muhammad Jones”), (Number: 105, Owner: “Hugh Martin”)}
D.{(Owner: “J. Smith”), (Owner: “W. Wei”), (Owner: “M. Jones”), (Owner: “H. Martin”)}
E.{(Owner: “John Smith”), (Owner: “Werner Wei”), (Owner: “John Smith”), (Owner: “Muhammad Jones”), (Owner: “Hugh Martin”)}
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标准答案
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思路分析
Start by understanding the operation: SELECT DISTINCT Owner FROM Account returns the unique values in the Owner column, removing any duplicates. Option A: {(Owner: “John Smith”), (Owner: “Werner Wei”), (Owner: “Muhammad Jones”), (Owner: “Hugh Martin”)} This matches the set of distinct owners observed in the table: John Smith appears twice but is listed once, Werner Wei appears once, Muhammad Jones appears once, and Hugh Martin appears once. The values are cor......Login to view full explanation

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