MySQL Interview Questions
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1. Paginate Users
Consider the following table:
CREATE TABLE users (
id BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY,
username VARCHAR(50) NOT NULL
);
The following query is used to paginate the table:
SELECT * FROM users ORDER BY username LIMIT 5 OFFSET 15;
Select all the true statements about this method of pagination.
(multiple correct answers possible)
2. Item Archive
Fill in the blanks so that the trigger item_delete inserts name from item table to the item_archive table, after a row from the table item is deleted.
CREATE TABLE item (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(50) NOT NULL,
quantity INT NOT NULL
);
CREATE TABLE item_archive (
archive_id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(50) NOT NULL
);
DELIMITER $$
CREATE item_delete ON item
FOR EACH ROW
BEGIN
INSERT INTO item_archive(name) VALUES ();
END;
$$
DELIMITER ;
See the example case for more details.
3. Registrations
Consider the following DDL statement:
CREATE TABLE registrations (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(50) NOT NULL,
create_date DATE NOT NULL,
last_activity DATE NOT NULL
);
Fill in the blanks so that the following select returns all registrations that were last active at least 30 days after being created.
SELECT name, create_date, last_activity FROM registrations
WHERE >= (, INTERVAL 30 DAY);
See the example case for more details.