题目
题目
单项选择题

Question at position 24 What is the difference between a PRIMARY KEY and a UNIQUE KEY?None of thesePrimary key cannot be a date variable whereas unique key can beWe can have only one primary key in a table while we can have multiple unique keysPrimary key can store null value, whereas a unique key cannot store null value.

选项
A.None of these
B.Primary key cannot be a date variable whereas unique key can be
C.We can have only one primary key in a table while we can have multiple unique keys
D.Primary key can store null value, whereas a unique key cannot store null value.
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标准答案
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思路分析
In this question, we are comparing a PRIMARY KEY and a UNIQUE KEY. Option 1: None of these. This would be incorrect because there is a true, well-known difference between primary keys and unique keys in relational databases. O......Login to view full explanation

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