MySQL - Quiz

4 esercizi

SVOLGI

INFO

Anomalies

Which of the following anomalies may occur with the Repeatable Read isolation level?

Lost Updates.

Dirty Read.

Non-repeatable read.

Phantom records.

None.

Scelta multipla

A MySQL statement

The MySQL statement to add a foreign key Fk to an existing table tab2 referencing to primary key Pk in tab1 is:

ALTER TABLE tab1 ADD FOREIGN KEY (Fk)

REFERENCES tab2(Pk);

ALTER TABLE tab2 ADD FOREIGN KEY (Fk)

REFERENCES tab1(Pk);

ALTER TABLE tab2 ADD FOREIGN KEY (Fk)

REFERENCES Pk (tab1);

ALTER TABLE tab1 ADD FOREIGN KEY (Pk)

REFERENCES tab2(Fk);

Scelta multipla

An output

What is the output of the following commands?

SET @val = 10;
SELECT Titles FROM books
WHERE Price < @val;

The books of unknown cost.

An error message.

The books that cost less than 10 euro.

The books that contain 'val' in the title.

Scelta multipla

A database table called users

Which MySQL statement is used to create a database table called users?

CREATE DATABASE users

CREATE DATABASE TABLE users

CREATE TABLE users

CREATE users

Scelta multipla