BASIC COMPUTER CONCEPTS
INFORMATION SYSTEMS VS INFORMATION TECHNOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Only primary key values must be unique
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Only foreign key values must be unique
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Both primary and foreign key values must be unique
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Neither primary nor foreign key values must be unique
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Detailed explanation-1: -The values present in the foreign key column must be present in the primary key of the related table.
Detailed explanation-2: -Answer and Explanation: The statement that is false regarding primary key is: Only parent tables must have a primary key.
Detailed explanation-3: -A primary key uniquely identifies a row in a table, while a foreign key is used to link two tables together by referencing the primary key of the related table. The most important difference that you should note here is that a primary key cannot have a NULL value, whereas a foreign key can accept NULL values.
Detailed explanation-4: -A primary key constraint is a column that uniquely identifies every row in the table of the relational database management system, while a foreign key is a column that creates a relationship between two tables. The primary Key never accepts null values, whereas the foreign key may accept multiple null values.