Question

what are the two characteristics of a primary key
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Answer 1

Answer:

A primary key has the following characteristics:

There can only be one primary key for a table.

The primary key consists of one or more columns.

The primary key enforces the entity integrity of the table.

All columns defined must be defined as NOT NULL.

The primary key uniquely identifies a row.

Explanation:

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Answer 2

Explanation:

1) the primary key uniquely identifies a row.

2) the primary key enforces the entity integrity of the time table.