SQL MCQ Quiz - Objective Question with Answer for SQL - Download Free PDF

The correct answer is LIKE.

Key Points

• The LIKE keyword is used in SQL to search for a specified pattern in a column.
• It is often used with wildcards to perform pattern matching within a query.
• There are two main wildcards used in conjunction with LIKE:
  • The percentage sign (%) represents zero, one, or multiple characters.
  • The underscore (_) represents a single character.
• For example:
  • SELECT * FROM Customers WHERE City LIKE 'New%'; - This query finds any values that start with "New".
  • SELECT * FROM Customers WHERE City LIKE '_ew%'; - This query finds any values where the second and third characters are "ew".

Additional Information

• The LIKE keyword is case-insensitive in some database systems, but case-sensitive in others.
• Using wildcards can impact the performance of SQL queries, especially with large datasets.
• The LIKE keyword is primarily used in SELECT, UPDATE, and DELETE statements.
• Other SQL keywords related to pattern matching include SIMILAR TO and REGEXP (regular expressions).

The correct answer is ALTER TABLE table_name ADD FOREIGN KEY(attribute name) REFERENCES referenced_table_name(attribute name).

Key Points

• To add a foreign key constraint, the ALTER TABLE statement is used to modify the existing table structure.
• The syntax for adding a foreign key is:
  • ALTER TABLE table_name ADD FOREIGN KEY (attribute_name) REFERENCES referenced_table_name(attribute_name);
• This statement ensures referential integrity by creating a link between the foreign key in one table and the primary key in another table.
• It is important to specify the table and attribute names correctly for both the foreign key and the referenced primary key.

Additional Information

• Foreign keys help maintain data consistency and integrity across related tables.
• They prevent actions that would destroy the relationships between tables, such as deleting a record that is referenced by a foreign key in another table.
• Foreign key constraints can also enforce cascading actions such as ON DELETE CASCADE or ON UPDATE CASCADE, which automatically update or delete dependent records.
• Properly defining foreign keys is crucial in database design to ensure data is stored in a normalized and efficient manner.

The correct answer is LIKE.

Key Points

• The LIKE keyword is used in SQL to search for a specified pattern in a column.
• It is often used with wildcards to perform pattern matching within a query.
• There are two main wildcards used in conjunction with LIKE:
  • The percentage sign (%) represents zero, one, or multiple characters.
  • The underscore (_) represents a single character.
• For example:
  • SELECT * FROM Customers WHERE City LIKE 'New%'; - This query finds any values that start with "New".
  • SELECT * FROM Customers WHERE City LIKE '_ew%'; - This query finds any values where the second and third characters are "ew".

Additional Information

• The LIKE keyword is case-insensitive in some database systems, but case-sensitive in others.
• Using wildcards can impact the performance of SQL queries, especially with large datasets.
• The LIKE keyword is primarily used in SELECT, UPDATE, and DELETE statements.
• Other SQL keywords related to pattern matching include SIMILAR TO and REGEXP (regular expressions).

The correct answer is ALTER TABLE table_name ADD FOREIGN KEY(attribute name) REFERENCES referenced_table_name(attribute name).

Key Points

• To add a foreign key constraint, the ALTER TABLE statement is used to modify the existing table structure.
• The syntax for adding a foreign key is:
  • ALTER TABLE table_name ADD FOREIGN KEY (attribute_name) REFERENCES referenced_table_name(attribute_name);
• This statement ensures referential integrity by creating a link between the foreign key in one table and the primary key in another table.
• It is important to specify the table and attribute names correctly for both the foreign key and the referenced primary key.

Additional Information

• Foreign keys help maintain data consistency and integrity across related tables.
• They prevent actions that would destroy the relationships between tables, such as deleting a record that is referenced by a foreign key in another table.
• Foreign key constraints can also enforce cascading actions such as ON DELETE CASCADE or ON UPDATE CASCADE, which automatically update or delete dependent records.
• Properly defining foreign keys is crucial in database design to ensure data is stored in a normalized and efficient manner.