Question : What is primary key. Choose from the options given below -
Option 1: A Primary key is a field or a combination of fields that can uniquely identify a row/tuple in a table/relation.
Option 2: A Primary key in table/relation is any non-primary key field which also stores unique values for each row just like a primary-key does. But only one key is designated as primary key. So unique refers to a unique non-key field of a table.
Option 3: A Primary key is a field of a table which is the primary key of another table through a foreign key a relationship is established between two tables.
Option 4: None of the above
Correct Answer: A Primary key is a field or a combination of fields that can uniquely identify a row/tuple in a table/relation.
Solution : The column or columns that each row in a table uses to uniquely identify itself is known as the primary key. For Optim to insert, update, restore, or delete data from a database table, the table must contain a primary key.
Hence the correct answer is option 1.
Question : What are the two common fields used in a relationship between tables?
Option 1: Key fields
Option 2: Primary field
Option 3: Secondary field
Question : According to ____________________ integrity, the values appearing in the given attributes of any tuple in the referencing relation must also appear in the defined attributes of at least one tuple in the referred relation.
Option 1: Referential
Option 2: Primary
Option 3: Referencing
Option 4: Specific
Question : Which of the following statements is true?
Option 1: A Primary key is also a candidate key.
Option 2: Each relation has at least one foreign key.
Option 3: Foreign keys can't have null values.
Option 4: A Primary key is also an alternate key.
Question : An attribute that uniquely identifies the rows of a table is known as the ----- key.
Option 1: primary
Option 2: candidate
Option 3: composite
Option 4: foreign
Question :
A compound key -
Option 1: Is made up a several pieces of information
Option 2: Uniquely identifies an item in a list
Option 3: Both (1) and (2)
Option 4: Is a combination of each unique key
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