MySQL MCQ Questions with answers and solutions Page 163

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Mr. Dubey

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Q. Which command is used to remove a table from a database?

(A) DELETE TABLE
(B) REMOVE TABLE
(C) DROP TABLE
(D) DESTROY TABLE

💬 Discuss

✅ Correct Answer: (C) DROP TABLE

Explanation: `DROP TABLE` deletes the table and all of its data permanently.

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Q. Which of the following is a valid way to create an index?

(A) CREATE KEY idx_name ON table(column);
(B) MAKE INDEX idx_name ON table(column);
(C) CREATE INDEX idx_name ON table(column);
(D) SET INDEX ON table(column);

💬 Discuss

✅ Correct Answer: (C) CREATE INDEX idx_name ON table(column);

Explanation: `CREATE INDEX` is the correct syntax to create an index in MySQL.

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Mr. Dubey

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📊 MySQL

Q. What does this query do?

Code:

SELECT name FROM students WHERE name LIKE 'A%';

(A) Selects students with names starting with A
(B) Selects students with names ending in A
(C) Selects students with names containing A
(D) Selects all students

💬 Discuss

✅ Correct Answer: (A) Selects students with names starting with A

Explanation: `'A%'` matches strings that start with 'A'.

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Mr. Dubey

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Q. Which clause is used to limit the number of rows returned?

(A) RESTRICT
(B) LIMIT
(C) ROWNUM
(D) TOP

💬 Discuss

✅ Correct Answer: (B) LIMIT

Explanation: `LIMIT` is used to specify the number of records to return.

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Mr. Dubey

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Q. How do you rename a column in MySQL?

(A) RENAME COLUMN old TO new;
(B) ALTER TABLE t RENAME old TO new;
(C) ALTER TABLE t CHANGE old new datatype;
(D) SET COLUMN old AS new;

💬 Discuss

✅ Correct Answer: (C) ALTER TABLE t CHANGE old new datatype;

Explanation: `ALTER TABLE ... CHANGE old_name new_name datatype;` is used to rename a column.

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Mr. Dubey

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Q. Which keyword is used to define a foreign key in MySQL?

(A) EXTERNAL KEY
(B) FOREIGN KEY
(C) REF KEY
(D) LINK KEY

💬 Discuss

✅ Correct Answer: (B) FOREIGN KEY

Explanation: `FOREIGN KEY` enforces referential integrity between two related tables.

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Mr. Dubey

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Q. Which type of JOIN returns only matching rows from both tables?

(A) LEFT JOIN
(B) RIGHT JOIN
(C) FULL JOIN
(D) INNER JOIN

💬 Discuss

✅ Correct Answer: (D) INNER JOIN

Explanation: `INNER JOIN` returns rows when there is at least one match in both tables.

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Q. What will this query do?

Code:

SELECT AVG(score) FROM results;

(A) Finds the maximum score
(B) Finds the minimum score
(C) Finds the average score
(D) Finds the sum of scores

💬 Discuss

✅ Correct Answer: (C) Finds the average score

Explanation: `AVG()` returns the average of a numeric column.

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Mr. Dubey

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Q. Which constraint ensures that all values in a column are different?

(A) NOT NULL
(B) DEFAULT
(C) UNIQUE
(D) INDEX

💬 Discuss

✅ Correct Answer: (C) UNIQUE

Explanation: The `UNIQUE` constraint ensures all values in a column are distinct.

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Mr. Dubey

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📊 MySQL

Q. How can you select the top 5 rows in a table?

(A) SELECT * FROM table LIMIT 5;
(B) SELECT TOP 5 FROM table;
(C) SELECT LIMIT 5 FROM table;
(D) SELECT FIRST 5 FROM table;

💬 Discuss

✅ Correct Answer: (A) SELECT * FROM table LIMIT 5;

Explanation: `LIMIT 5` returns the first 5 rows from the result set.

MySQL MCQs with answers Page - 163

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