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What is the purpose of the COUNT() function in MySQL?
- A) To return the number of rows in a table
- B) To calculate the total value of a numeric column
- C) To return the average value of a numeric column
- D) To concatenate values from multiple rows into a single string
Answer: A) To return the number of rows in a table
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Which SQL command is used to add a foreign key constraint to a table in MySQL?
- A) ADD FOREIGN KEY
- B) CREATE FOREIGN KEY
- C) ALTER FOREIGN KEY
- D) SET FOREIGN KEY
Answer: B) CREATE FOREIGN KEY
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What is the purpose of the UNIQUE constraint in MySQL?
- A) To ensure that each row in a table is unique
- B) To ensure that a column does not contain null values
- C) To specify the default value for a column
- D) To specify the primary key for a table
Answer: A) To ensure that each row in a table is unique
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Which SQL function is used to return the lowercase version of a string in MySQL?
- A) LOWER()
- B) LCASE()
- C) TOLOWER()
- D) CONVERT()
Answer: A) LOWER()
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What is the purpose of the CASCADE option in a foreign key constraint in MySQL?
- A) To specify the action to perform when a foreign key constraint is violated
- B) To specify the action to perform when a primary key constraint is violated
- C) To specify the action to perform when a column is updated
- D) To specify the action to perform when a column is deleted
Answer: A) To specify the action to perform when a foreign key constraint is violated
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Which SQL command is used to create a view in MySQL?
- A) CREATE VIEW
- B) ADD VIEW
- C) MAKE VIEW
- D) INSERT VIEW
Answer: A) CREATE VIEW
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What is the purpose of the EXISTS operator in MySQL?
- A) To check if a value exists in a specified range
- B) To check if a subquery returns any rows
- C) To filter rows based on a specified condition
- D) To specify the columns to retrieve in the result set
Answer: B) To check if a subquery returns any rows
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Which SQL function is used to return the uppercase version of a string in MySQL?
- A) UPPER()
- B) UCASE()
- C) TOUPPER()
- D) CONVERT()
Answer: A) UPPER()
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What is the purpose of the AS keyword in MySQL?
- A) To specify the table to perform the operation on
- B) To specify the columns to retrieve in the result set
- C) To rename a column or table in the result set
- D) To filter rows based on a specified condition
Answer: C) To rename a column or table in the result set
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Which SQL command is used to remove a foreign key constraint from a table in MySQL?
- A) DELETE FOREIGN KEY
- B) REMOVE FOREIGN KEY
- C) DROP FOREIGN KEY
- D) ERASE FOREIGN KEY
Answer: C) DROP FOREIGN KEY
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