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Web-Centric > Lecture 9 - Stateful Web > Flashcards

Lecture 9 - Stateful Web Flashcards

1
Q

What does PDO stand for?

A

PHP Data Object

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2
Q

To configure the PDO to throw an exception any time there’s a failure?

A

Use the PDO’s setAttribute() method

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3
Q

What is the exec() method used for?

A

Queries can be sent to a MYSQL database using it.

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4
Q

What does PDO do?

A

Identifies that the connection to a database has been established

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5
Q

If PHP cannot handle PDO, what will it do?

A

Throws a php exception

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6
Q

What does the try-catch statement do?

A 
try {
do something
}
catch (Exception type $e){
handle exception
}
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7
Q

What does this code do?

A

This function returns a PHP Data Object (PDO)

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8
Q

IF this PDO code can’t be performed, what happens?

A

PHP will throw an exception

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9
Q

What does PHP do with a database once a connection is no longer needed?

A

It automatically disconnects

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10
Q

How do you force PHP to close a connection?

A

$pdo = null

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11
Q

How do you connect to a database with procedural php?

A

$variable_name = mysql_connect(hostname, username, password);

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12
Q

How do you close a connection to a mysql database with procedural php?

A

mysql_close();

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13
Q

What must be do before answering a query?

A

Establish a database connection

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14
Q

What are the best practices of querying a database?

A

Establish a connection at the start of the php script

During development, leave clues in case of issues when passing queries to the server. (relevant error messages)

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15
Q

Name three sql queries

A

DELETE, INSERT, UPDATE

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16
Q

PDO Method: How do we create a table?

A

$sql = ‘CREATE TABLE jokes(id INT NOT NULLAUTO_INCREMENT PRIMARY KEY,
joketext TEXT,
jokedate DATE NOT NULL,
)

$pdo->exec($sql)

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17
Q

PDO Method: How do we update a table?

A

$sql = ‘UPDATE joke SET jokedate = “2012” WHERE joke text LIKE “%chicken%”;

$affectedRows = $pdo ->exec($sql)

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18
Q

PDO Method: How do we SELECT?

A 
$sql = 'SELECT * FROM tablename'; 
$result = $pdo->query($sql);
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19
Q

What makes SELECT queries different from other queries?

A

They produce results

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20
Q

Procedural Method: How do we send SQL queries through php?

A

$variable_name = mysqli_query(sql statement);

Example:
$variable_name = mysqli_query(SELECT*FROM customers);

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21
Q

What would the result set of a query contain?

A

A list of all the entries returned from the query

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22
Q

Which PHP functions are needed to connect to the database using procedural php?

A

mysqli_connect()
mysql_set_chart()
mysqli_select_db()

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23
Q

What does mysqli_connect() do?

A

Connects to the database

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24
Q

What does mysql_set_chartset() do?

A

Indicates the character set to be used for
communications between PHP and the DB

Must match the character set used by HTML pages,
DB and its tables

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25
Q

What does mysql_select_db() do?

A

Indicates the database to be used for queries.

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26
Q

How would you add a new joke from a user, using php?

A

if (isset($_GET[‘addjoke’]))
{
include ‘form.html.php’;
exit()

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27
Q

When deleting a record, how will we identify which once we want removed?

A

By it’s ID

28
Q

Can vars in the main script be accessed or edited from an included file?

A

Yes. is can cause issues likes overwrites. Functions can protect you from this happening.

29
Q

What is a function’s scope?

A

Variables created inside a function exist only in that function

30
Q

Can vars from the mains script by accessed from within functions?

A

No.

31
Q

How can we mitigate issues that function and global variable scope can cause?

A

Keep track of var names and scripts

Keep track of which variables work within which scripts

32
Q

What are the two ways we can use vars in a function?

A

Importing a variable

using the $GLOBALS array

33
Q

What is the magic quotes function?

A
  • Causes as many issues as it solves
  • Only works in some circumstances
  • Functionality depends on site’s character encoding
  • Adds backslashes to escape characters expected in a sql query, even if it’s just plain text
  • We still need to work with it for now
34
Q

How do we import a variable to a function?

A

Using the global statement you can import more than one variable.

If you modify an imported variable inside the function, it’s value is modified outside the function.

35
Q

If you edit an imported variable inside a function, is it affected outside the function?

A

Yes, the value is modified outside the function as well

36
Q

How do we use the $GLOBALS array?

A

Access with $GLOBALS[‘variable_name]

37
Q

What is the advantage to using the $GLOBALS array?

A

Keeps variables with a function scope separate

38
Q

Name some super global arrays

A 
$_GET
$_POST
$_COOKIE
$_FILES
$_REQUEST
$_SERVER
$_SESSION
$_ENV
39
Q

Why do we have a stateful web?

A

Most programs preserve some state when they are closed.

There was a need for similar functionality in dynamic sites

40
Q

What does HTTP stand for?

A

HyperText Transfer Protocol

41
Q

What is HTTP responsible for?

A

Handling Requests

42
Q

What are the limitations of HTTP?

A

It is a stateless technology

Provides no user tracking

43
Q

What is the solution to the limitations of HTTP?

A

Cookies…and cream

44
Q

What is a Php cookie?

A

A name-value pair associated with a given website

45
Q

Where is a cookie stored?

A

On the client side and limited to 4kb of data

46
Q

Once the cookie is set, all following requests of the site will include what?

A

the cookie for that site

47
Q

When does a cookie expire?

A

When it becomes out of date or the browser is closed.

48
Q

Can cookies be accessed from any website?

A

Only the website that issued them

49
Q

How do we create a cookie?

A

Use the setcookie() function

50
Q

Do cookies behave the same way in all browsers?

A

No

51
Q

What is the one necessary parameter of a cookie?

A

The name

52
Q

What info will be kept int he cookie?

A

The value

The expiry time

53
Q

How would we set the cookie to expire in one hour

A

time() + 3600

54
Q

The setcookie() function’s domain allows you to:

A

Restrict the cookie’s access to a specific domain.

55
Q

How do we limit the cookie requests to only be sent over a secure connection?

A

Use ‘secure’

56
Q

httpOnly is used for what?

A

If set to 1, tells browser to prevent JavaSCript code on the site from seeing the cookie being sent

57
Q

What are the limitations of cookies?

A

Browsers limit the number and size of cookies per website

Browsers delete old cookies to make space for new ones

58
Q

What is the max size of a cookie?

A

4kb

59
Q

What do we use if we need more space than a cookie can provide?

A

A session

60
Q

What one value is stored in the browser to allow for a session?

A

The session ID, stored as a cookie.

61
Q

When a session is started, what does PHP generate?

A

PHP generates a randon session ID, a reference to that session, and its stored data

62
Q

Where is the value of the session set?

A

The special $_SESSION array

63
Q

What happens if an existing session ID is found when starting a session?

A

PHP restores the variables that belong to that session

64
Q

How do we set a session variable in the special $_SESSION array?

A

$ …_…SESSION… […’ name…’] = value

65
Q

How do we remove a variable from the current session?

A

unset SESSION name

Web-Centric (10 decks)

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