COMPUTER APPLICATIONS
DATABASE MANAGEMENT SYSTEMS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Which key ensure that data in a field must only appear once in the whole table.
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Candidate key field
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Foreign key
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Primary key field
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Alternate key field
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Explanation:
Detailed explanation-1: -Foreign key columns are frequently used in join criteria when the data from related tables is combined in queries by matching the column or columns in the foreign key constraint of one table with the primary or unique key column or columns in the other table.
Detailed explanation-2: -A table can have only one primary key. Also, we can create a date variable as a primary key in a table. Unique key also determines each row of the table uniquely, but it can take null value into.
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