n5aq.md

Don't forget to hit the ⭐ if you like this repo.

PHP: MySQL and CRUD

Set A

Please answer the following 50 multiple-choice questions to test your knowledge in MySQL and CRUD. You must place your answer file in the submission folder. Within the submission/Q5/set_a folder, create a folder called your github_id.

1. Which of the following is a popular open-source relational database management system?

   • a) MySQL
   • b) MongoDB
   • c) Oracle
   • d) SQLite

2. How do you establish a connection to a MySQL database in PHP?

   • a) mysqli_connect()
   • b) mysql_connect()
   • c) pdo_connect()
   • d) db_connect()

3. Which PHP function is used to execute an SQL query?

   • a) mysql_query()
   • b) mysqli_query()
   • c) pdo_query()
   • d) db_query()

4. What does SQL stand for?

   • a) Structured Query Language
   • b) Sequential Query Language
   • c) Specific Query Language
   • d) Structured Question Language

5. How do you fetch a single row of data from a MySQL query result in PHP?

   • a) mysqli_fetch_row()
   • b) mysqli_fetch_array()
   • c) mysqli_fetch_assoc()
   • d) mysqli_fetch_object()

6. Which PHP function is used to retrieve the number of rows returned by a MySQL query?

   • a) mysql_num_rows()
   • b) mysqli_num_rows()
   • c) pdo_num_rows()
   • d) db_num_rows()

7. How do you escape special characters in a string before inserting it into a MySQL database?

   • a) mysql_escape_string()
   • b) mysqli_escape_string()
   • c) pdo_escape_string()
   • d) db_escape_string()

8. Which SQL statement is used to insert data into a MySQL database?

   • a) INSERT INTO
   • b) UPDATE
   • c) SELECT
   • d) DELETE FROM

9. How do you retrieve the ID of the last inserted row in a MySQL database using PHP?

   • a) mysql_insert_id()
   • b) mysqli_insert_id()
   • c) pdo_insert_id()
   • d) db_insert_id()

10. What is the result of the following PHP code?

    $conn = mysqli_connect("localhost", "username", "password", "database");
    if (!$conn) {
        die("Connection failed: " . mysqli_connect_error());
    }

    • a) Establishes a connection to the MySQL database
    • b) Prints "Connection failed" if the connection is unsuccessful
    • c) Terminates the script execution if the connection fails
    • d) All of the above

11. Which PHP function is used to close a connection to a MySQL database?

    • a) mysql_close()
    • b) mysqli_close()
    • c) pdo_close()
    • d) db_close()

12. What does the mysqli_fetch_array() function return in PHP?

    • a) An associative array
    • b) A numeric array
    • c) Both associative and numeric arrays
    • d) A single value

13. How do you execute a prepared statement with placeholders in PHP using MySQLi?

    • a) mysqli_prepare()
    • b) mysqli_execute()
    • c) mysqli_bind_param()
    • d) mysqli_stmt_execute()

14. Which PHP function is used to handle errors during MySQL database operations?

    • a) mysql_error()
    • b) mysqli_error()
    • c) pdo_error()
    • d) db_error()

15. How do you retrieve the number of affected rows after an UPDATE or DELETE query in MySQLi?

    • a) $mysqli->affected_rows
    • b) mysqli_affected_rows()
    • c) $pdo->affected_rows
    • d) db_affected_rows()

16. Which PHP function is used to handle transactions in MySQL databases?

    • a) mysql_transaction()
    • b) mysqli_transaction()
    • c) pdo_transaction()
    • d) db_transaction()

17. How do you retrieve the auto-incremented ID of the last inserted row in PDO?

    • a) $pdo->lastInsertId()
    • b) pdo_last_insert_id()
    • c) $pdo->insertId()
    • d) pdo_insert_id()

18. Which SQL statement is used to update data in a MySQL database?

    • a) UPDATE
    • b) INSERT INTO
    • c) SELECT
    • d) DELETE FROM

19. How do you prevent SQL injection in PHP when working with MySQL databases?

    • a) Sanitize user input using filter functions
    • b) Use prepared statements with placeholders
    • c) Escape special characters in SQL queries
    • d) All of the above

20. What does the SQL statement SELECT * FROM users WHERE age > 25 do?

    • a) Retrieves all users with an age greater than 25
    • b) Retrieves all users with an age less than 25
    • c) Retrieves all users from the "age" table
    • d) Retrieves all columns from the "users" table

21. How do you retrieve the number of rows returned by a PDO query?

    • a) $pdo->rowCount()
    • b) pdo_num_rows()
    • c) count($pdo)
    • d) count($pdo->fetchAll())

22. What is the result of the following code?

    $sql = "SELECT * FROM users";
    $result = mysqli_query($conn, $sql);
    $count = mysqli_num_rows($result);
    echo $count;

    • a) Prints the number of rows in the "users" table
    • b) Prints the number of columns in the "users" table
    • c) Prints the result of the query
    • d) Error

23. Which PHP function is used to fetch the next row from a MySQL query result?

    • a) mysql_fetch_row()
    • b) mysqli_fetch_row()
    • c) pdo_fetch_row()
    • d) db_fetch_row()

24. How do you retrieve the value of a specific column from a MySQL query result in PHP?

    • a) By specifying the column name in the fetch function
    • b) By accessing the column index in the fetch function
    • c) By using the mysql_result() function
    • d) By using the mysqli_result() function

25. Which PHP function is used to free the memory associated with a MySQL query result?

    • a) mysql_free_result()
    • b) mysqli_free_result()
    • c) pdo_free_result()
    • d) db_free_result()

26. How do you retrieve the number of fields (columns) in a MySQL query result in PHP?

    • a) $result->num_fields()
    • b) mysqli_num_fields($result)
    • c) $result->field_count()
    • d) count($result)

27. Which SQL statement is used to delete data from a MySQL database?

    • a) DELETE FROM
    • b) UPDATE
    • c) INSERT INTO
    • d) SELECT

28. How do you retrieve the value of a specific field (column) from a MySQL query result in PHP?

    • a) By specifying the field name in the fetch function
    • b) By accessing the field index in the fetch function
    • c) By using the mysql_field_result() function
    • d) By using the mysqli_field_result() function

29. What is the result of the following code?

    $sql = "SELECT COUNT(*) FROM users";
    $result = mysqli_query($conn, $sql);
    $count = mysqli_fetch_array($result)[0];
    echo $count;

    • a) Prints the number of rows in the "users" table
    • b) Prints the number of columns in the "users" table
    • c) Prints the result of the query
    • d) Error

30. How do you retrieve the error message from a failed MySQL query in PHP?

    • a) $conn->error
    • b) mysqli_error()
    • c) $pdo->error
    • d) db_error()

31. Which PHP function is used to fetch all rows from a MySQL query result at once?

    • a) mysql_fetch_all()
    • b) mysqli_fetch_all()
    • c) pdo_fetch_all()
    • d) db_fetch_all()

32. How do you retrieve the current auto-increment value for a table in MySQL using PHP?

    • a) SHOW AUTO_INCREMENT FROM table
    • b) SELECT AUTO_INCREMENT FROM table
    • c) AUTO_INCREMENT()
    • d) mysql_auto_increment()

33. Which PHP function is used to escape special characters in a string before inserting it into a MySQL database?

    • a) mysql_escape_string()
    • b) mysqli_escape_string()
    • c) pdo_escape_string()
    • d) db_escape_string()

34. How do you retrieve the number of affected rows after an INSERT query in MySQLi?

    • a) $mysqli->affected_rows
    • b) mysqli_affected_rows()
    • c) $pdo->affected_rows
    • d) db_affected_rows()

35. What is the result of the following code?

    $sql = "SELECT * FROM users WHERE id = '1'";
    $result = mysqli_query($conn, $sql);
    $row = mysqli_fetch_assoc($result);
    echo $row['name'];

    • a) Prints the name of the user with ID 1
    • b) Prints the name of the first user in the table
    • c) Prints the ID of the user with name '1'
    • d) Error

36. How do you retrieve the number of rows affected by an UPDATE or DELETE query in PDO?

    • a) $pdo->rowCount()
    • b) pdo_num_rows()
    • c) count($pdo)
    • d) count($pdo->fetchAll())

37. Which PHP function is used to handle transactions in PDO?

    • a) $pdo->transaction()
    • b) pdo_transaction()
    • c) $pdo->beginTransaction()
    • d) pdo_begin_transaction()

38. How do you retrieve the auto-incremented ID of the last inserted row in MySQLi?

    • a) $mysqli->insert_id
    • b) mysqli_insert_id()
    • c) $mysqli->lastInsertId()
    • d) mysqli_last_insert_id()

39. What is the result of the following code?

    $sql = "INSERT INTO users (name, email) VALUES ('John Doe', '[email protected]')";
    $result = mysqli_query($conn, $sql);
    if ($result === true) {
        echo "User inserted successfully.";
    } else {
        echo "Error inserting user.";
    }

    • a) Prints "User inserted successfully" if the query is successful
    • b) Prints "Error inserting user" if the query fails
    • c) Prints nothing
    • d) Error

40. How do you retrieve the number of fields (columns) in a MySQL query result in PDO?

    • a) $result->columnCount()
    • b) pdo_num_fields()
    • c) count($result)
    • d) count($result->fetch())

41. Which PHP function is used to fetch the next row from a MySQL query result in PDO?

    • a) $result->nextRow()
    • b) pdo_fetch_row()
    • c) $result->fetch()
    • d) pdo_next_row()

42. What is the result of the following code?

    $sql = "SELECT * FROM users";
    $result = mysqli_query($conn, $sql);
    $count = mysqli_num_fields($result);
    echo $count;

    • a) Prints the number of fields (columns) in the "users" table
    • b) Prints the number of rows in the "users" table
    • c) Prints the result of the query
    • d) Error

43. How do you retrieve the value of a specific column from a MySQL query result in PDO?

    • a) By specifying the column name in the fetch function
    • b) By accessing the column index in the fetch function
    • c) By using the pdo_result() function
    • d) By using the pdo_fetch_column() function

44. Which PHP function is used to free the memory associated with a MySQL query result in PDO?

    • a) $result->free()
    • b) pdo_free_result()
    • c) $result->close()
    • d) pdo_free_memory()

45. How do you retrieve the number of rows returned by a MySQL query in PDO?

    • a) $result->rowCount()
    • b) pdo_num_rows()
    • c) count($result)
    • d) count($result->fetch())

46. What is the result of the following code?

    $sql = "SELECT * FROM users WHERE age > 25";
    $result = mysqli_query($conn, $sql);
    $count = mysqli_num_rows($result);
    echo $count;

    • a) Prints the number of users with an age greater than 25
    • b) Prints the number of users with an age less than 25
    • c) Prints the result of the query
    • d) Error

47. How do you retrieve the error message from a failed MySQL query in PDO?

    • a) $pdo->errorInfo()
    • b) pdo_error()
    • c) $pdo->errorMessage()
    • d) pdo_error_message()

48. Which PHP function is used to fetch all rows from a MySQL query result at once in PDO?

    • a) $result->fetchAll()
    • b) pdo_fetch_all()
    • c) $result->getAll()
    • d) pdo_get_all()

49. How do you retrieve the current auto-increment value for a table in MySQL using PHP and MySQLi?

    • a) SHOW AUTO_INCREMENT FROM table
    • b) SELECT AUTO_INCREMENT FROM table
    • c) AUTO_INCREMENT()
    • d) mysqli_auto_increment()

50. What is the result of the following code?

    $sql = "DELETE FROM users WHERE id = 1";
    $result = mysqli_query($conn, $sql);
    if ($result) {
        echo "User deleted successfully.";
    } else {
        echo "Error deleting user.";
    }

    • a) Prints "User deleted successfully" if the query is successful
    • b) Prints "Error deleting user" if the query fails
    • c) Prints nothing
    • d) Error

Contribution 🛠️

Please create an Issue for any improvements, suggestions or errors in the content.

You can also contact me using Linkedin for any other queries or feedback.