Database Reference
In-Depth Information
$sth
=
$dbh
->
exec
(
"
CREATE TABLE deck
(
face ENUM('A', 'K', 'Q', 'J', '10', '9', '8',
'7', '6', '5', '4', '3', '2') NOT NULL,
suit ENUM('hearts', 'diamonds', 'clubs', 'spades') NOT NULL
)
"
);
$face_array
=
array
(
"A"
,
"K"
,
"Q"
,
"J"
,
"10"
,
"9"
,
"8"
,
"7"
,
"6"
,
"5"
,
"4"
,
"3"
,
"2"
);
$suit_array
=
array
(
"hearts"
,
"diamonds"
,
"clubs"
,
"spades"
);
# insert a "card" into the deck for each combination of suit and face
$sth
=
$dbh
->
prepare
(
"INSERT INTO deck (face,suit) VALUES(?,?)"
);
foreach
(
$face_array
as
$face
)
foreach
(
$suit_array
as
$suit
)
$sth
->
execute
(
array
(
$face
,
$suit
));
Shuffling the cards is a matter of issuing this statement:
SELECT
face
,
suit
FROM
deck
ORDER
BY
RAND
();
To do that and store the results in an array within a script, write a
shuffle_deck()
function that issues the query and returns the resulting values in an array (again shown
in PHP):
function
shuffle_deck
(
$dbh
)
{
$sth
=
$dbh
->
query
(
"SELECT face, suit FROM deck ORDER BY RAND()"
);
$sth
->
setFetchMode
(
PDO
::
FETCH_OBJ
);
return
(
$sth
->
fetchAll
());
}
Deal the cards by keeping a counter that ranges from 0 to 51 to indicate which card to
select. When the counter reaches 52, the deck is exhausted and should be shuffled again.
15.8. Selecting Random Items from a Set of Rows
Problem
You want to pick an item or items randomly from a set of values.
Solution
Randomize the values, then pick the first one (or the first few, if you need more than
one).
