SQLite - 5 - Primary Keys and Constraints MCQ

SQLite – Primary Keys and Constraints

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1. What is the primary purpose of a primary key in a database table?

To enforce uniqueness

To allow NULL values

To define data types

To create a foreign key

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2. Which keyword is used to specify a primary key constraint when creating a table?

PRIMARY

INDEX

KEY

UNIQUE

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3. In SQLite, can a table have more than one primary key?

Yes

Only if they are integers

Only if they are text

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4. What happens when you try to insert a duplicate value into a column with a primary key constraint?

The new value replaces the existing one

The new value is added with a new primary key

An error is raised and the insert fails

The existing value is deleted

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5. Which SQL command is used to remove a primary key constraint from a column in SQLite?

REMOVE PRIMARY KEY

ALTER TABLE

DELETE PRIMARY KEY

DROP PRIMARY KEY

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6. What is the purpose of the “NOT NULL” constraint in SQLite?

To allow NULL values in a column

To ensure that a column cannot have NULL values

To enforce a unique constraint

To specify that a column should have a default value

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7. How do you specify that a column should allow NULL values when creating a table in SQLite?

By using the NULL keyword

By using the ALLOW NULL keyword

By using the NOT NULL keyword

By using the NULLABLE keyword

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8. Which keyword is used to specify that a column should have a default value when creating a table?

SET VALUE DEFAULT

DEFAULT VALUE

DEFAULT

SET DEFAULT

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9. What is the purpose of the “CHECK” constraint when creating a table in SQLite?

To validate the data against a specific condition

To check for NULL values in columns

To enforce foreign key relationships

To verify the data types of columns

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10. How do you specify a default value for a column when creating a table in SQLite?

By using the DEFAULT keyword

By using the DEFAULT VALUE keyword

By using the SET DEFAULT keyword

By using the DEFAULT ATTRIBUTE keyword

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11. What is the purpose of the “UNIQUE” constraint on a column when creating a table in SQLite?

It enforces that the column cannot be NULL

It enforces that the column is the only one in the table

It enforces that the column values are unique

It enforces that the column has a unique name

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12. In SQLite, how do you specify a column as the primary key when creating a table?

By using the KEYWORD PRIMARY keyword

By using the PRIMARY COLUMN keyword

By using the PRIMARY ATTRIBUTE keyword

By using the PRIMARY KEY keyword

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13. What is the purpose of the “AUTOINCREMENT” keyword when creating a table in SQLite?

To automatically increment the primary key value

To automatically delete rows from a table

To automatically update records in a table

To automatically insert data into a table

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14. What happens if you try to create a table with a primary key that has a data type of TEXT?

The table is created with an error

The table is created without any issues

The table is created with a warning

The primary key is automatically converted to INTEGER

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15. Which SQL command is used to create a unique index on a column when creating a table in SQLite?

CREATE UNIQUE INDEX

CREATE INDEX

INDEX UNIQUE

UNIQUE INDEX

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16. What is the primary purpose of the “FOREIGN KEY” constraint when creating a table in SQLite?

To specify the primary key of the table

To create an index on the column

To link the table to another table

To enforce uniqueness of values in a column

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17. Which keyword is used to specify a foreign key constraint on a column when creating a table in SQLite?

REFERENCES

CONSTRAINT

FOREIGN KEY

FOREIGN

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18. How do you specify that a column should have a foreign key constraint when creating a table in SQLite?

By using the FOREIGN REFERENCE keyword

By using the FOREIGN ATTRIBUTE keyword

By using the REFERENCES keyword

By using the FOREIGN CONSTRAINT keyword

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19. What is the purpose of the “ON DELETE CASCADE” clause in a foreign key constraint?

It deletes the foreign key constraint

It deletes the referenced record

It deletes the parent record and its child records

It deletes all records in the table

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20. Which SQL command is used to remove a foreign key constraint from a column in SQLite?

DELETE FOREIGN KEY

ALTER TABLE

DROP FOREIGN KEY

REMOVE FOREIGN KEY

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21. What is the primary benefit of using primary keys and constraints in a SQLite database?

To improve database performance

To increase the size of the database

To allow for NULL values in columns

To enforce data integrity and accuracy

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22. How do you specify that a column should have a check constraint when creating a table in SQLite?

By using the CHECK CONSTRAINT keyword

By using the CHECK keyword

By using the ASSERT keyword

By using the CONSTRAINT keyword

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23. Which keyword is used to specify a column as the primary key and auto-incremented when creating a table in SQLite?

AUTOINCREMENT PRIMARY

PRIMARY KEY AUTOINCREMENT

PRIMARY AUTOINCREMENT

AUTO PRIMARY KEY

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24. In SQLite, how do you specify that a column should allow NULL values when creating a table?

By using the NULL keyword

By using the NOT NULL keyword

By using the NULLABLE keyword

By using the ALLOW NULL keyword

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25. What is the primary purpose of the “DEFAULT CURRENT_TIMESTAMP” constraint in SQLite?

To set the column to a default value of "CURRENT_DATE"

To set the column to the current date and time

To set the column to a default value of "CURRENT_TIMESTAMP"

To set the column to the current date

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26. Which keyword is used to specify that a column should have a unique constraint and a default value when creating a table in SQLite?

UNIQUE DEFAULT

DEFAULT UNIQUE VALUE

DEFAULT UNIQUE

UNIQUE DEFAULT VALUE

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SQLite – 5 – Primary Keys and Constraints MCQ