PHP and MySQL

Question 1

Q: What is MySQL?

Answer 1

A: A relational database management system (RDBMS) that stores and manages data.

Question 2

Q: How does PHP interact with MySQL?

Answer 2

A: PHP uses extensions like mysqli or PDO to interact with MySQL databases.

Question 3

Q: What is the difference between mysqli and PDO?

Answer 3

A: mysqli is specific to MySQL, while PDO supports multiple databases.

Question 4

Q: What is the default MySQL port?

Answer 4

A: Port 3306.

Question 5

Q: What PHP function is used to connect to a MySQL database using mysqli?

Answer 5

A: mysqli_connect().

Question 6

Q: How do you create a MySQL database connection with mysqli?

Answer 6

$conn = mysqli_connect(“host”, “username”, “password”, “database”);

Question 7

Q: What function checks if a database connection was successful?

Answer 7

A: mysqli_connect_errno().

Question 8

Q: How do you close a MySQL connection in PHP?

Answer 8

A: Use mysqli_close($conn);.

Question 9

Q: What exception is thrown for connection errors in PDO?

Answer 9

A: PDOException.

Question 10

Q: How do you set up a database connection using PDO?

Answer 10

$pdo = new PDO(“mysql:host=host;dbname=database”, “username”, “password”);

Question 11

Q: What function is used to execute a query in mysqli?

Answer 11

A: mysqli_query().

Question 12

Q: How do you execute a query using PDO?

Answer 12

A: Use the query() or prepare() method.

Question 13

Q: What function fetches data as an associative array in mysqli?

Answer 13

A: mysqli_fetch_assoc().

Question 14

Q: What method fetches data in PDO?

Answer 14

A: Use fetch() or fetchAll().

Question 15

Q: How do you handle errors during a query in mysqli?

Answer 15

A: Check mysqli_error($conn).

Question 16

Q: What are prepared statements in PHP?

Answer 16

A: A way to execute SQL queries with placeholders to prevent SQL injection.

Question 17

Q: How do you create a prepared statement in mysqli?

Answer 17

A: Use mysqli_prepare().

Question 18

Q: How do you bind parameters in a mysqli prepared statement?

Answer 18

A: Use mysqli_stmt_bind_param().

Question 19

Q: What function executes a prepared statement in mysqli?

Answer 19

A: mysqli_stmt_execute().

Question 20

Q: How do you use placeholders in PDO?

Answer 20

A: Use named (:name) or positional (?) placeholders in the query.

Question 21

Q: What function fetches all rows as an array in mysqli?

Answer 21

A: mysqli_fetch_all().

Question 22

Q: What method retrieves a single row in PDO?

Answer 22

A: fetch(PDO::FETCH_ASSOC).

Question 23

Q: How do you loop through rows in mysqli?

Answer 23

while ($row = mysqli_fetch_assoc($result)) {
// Process $row
}

Question 24

Q: How do you count the number of rows in a result set in mysqli?

Answer 24

A: Use mysqli_num_rows().

Question 25

Q: How do you count rows in a result set in PDO?

Answer 25

A: Use the rowCount() method.

Question 26

Q: How do you insert data into a MySQL database using PHP?

Answer 26

$query = “INSERT INTO table (column1, column2) VALUES (‘value1’, ‘value2’)”;
mysqli_query($conn, $query);

Question 27

Q: How do you update data in a MySQL database using PHP?

Answer 27

$query = “UPDATE table SET column1 = ‘value’ WHERE id = 1”;
mysqli_query($conn, $query);

Question 28

Q: How do you delete data from a MySQL database using PHP?

Answer 28

$query = “DELETE FROM table WHERE id = 1”;
mysqli_query($conn, $query);

Question 29

Q: How do you select data from a database using PHP?

Answer 29

$query = “SELECT * FROM table”;
$result = mysqli_query($conn, $query);

Question 30

Q: How do you handle SQL injection in PHP?

Answer 30

A: Use prepared statements or the mysqli_real_escape_string() function.

Question 31

Q: What is a database transaction?

Answer 31

A: A sequence of database operations executed as a single unit.

Question 32

Q: How do you start a transaction in mysqli?

Answer 32

A: Use mysqli_begin_transaction().

Question 33

Q: How do you commit a transaction in mysqli?

Answer 33

A: Use mysqli_commit().

Question 34

Q: How do you roll back a transaction in mysqli?

Answer 34

A: Use mysqli_rollback().

Question 35

Q: How do you manage transactions in PDO?

Answer 35

A: Use beginTransaction(), commit(), and rollBack() methods.

Question 36

Q: How do you check for query errors in mysqli?

Answer 36

A: Use mysqli_error($conn).

Question 37

Q: How do you enable exceptions for errors in PDO?

Answer 37

A: Set the error mode to exception:

$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

Question 38

Q: What function provides error information for prepared statements in mysqli?

Answer 38

A: mysqli_stmt_error().

Question 39

Q: What is the purpose of mysqli_report()?

Answer 39

A: To set reporting for MySQL errors and warnings.

Question 40

Q: How do you log database errors in PHP?

Answer 40

A: Use error_log() to write errors to a file or system log.