PHP : Function Reference : PDO Functions : PDOStatement->fetch()
PDOStatement {
mixed fetch(int fetch_style, int cursor_orientation, int cursor_offset); }
Fetches a row from a result set associated with a PDOStatement object. The
fetch_style parameter determines how PDO returns
the row.
Parameters
- fetch_style
-
Controls how the next row will be returned to the caller. This value
must be one of the PDO::FETCH_* constants,
defaulting to PDO::FETCH_BOTH .
PDO::FETCH_ASSOC : returns an array indexed by column
name as returned in your result set
PDO::FETCH_BOTH (default): returns an array indexed by
both column name and 0-indexed column number as returned in your
result set
PDO::FETCH_BOUND : returns TRUE and assigns the
values of the columns in your result set to the PHP variables to which
they were bound with the PDOStatement->bindColumn()
method
PDO::FETCH_CLASS : returns a new instance of the
requested class, mapping the columns of the result set to named
properties in the class. If fetch_style
includes PDO::FETCH_CLASSTYPE (e.g. PDO::FETCH_CLASS |
PDO::FETCH_CLASSTYPE ) then the name of the class is
determined from a value of the first column.
PDO::FETCH_INTO : updates an existing instance
of the requested class, mapping the columns of the result set to
named properties in the class
PDO::FETCH_LAZY : combines
PDO::FETCH_BOTH and PDO::FETCH_OBJ ,
creating the object variable names as they are accessed
PDO::FETCH_NUM : returns an array indexed by column
number as returned in your result set, starting at column 0
PDO::FETCH_OBJ : returns an anonymous object with
property names that correspond to the column names returned in your
result set
- cursor_orientation
For a PDOStatement object representing a scrollable cursor, this
value determines which row will be returned to the caller. This value
must be one of the PDO::FETCH_ORI_* constants,
defaulting to PDO::FETCH_ORI_NEXT . To request a
scrollable cursor for your PDOStatement object, you must set the
PDO::ATTR_CURSOR attribute to
PDO::CURSOR_SCROLL when you prepare the SQL
statement with PDO->prepare().
- offset
-
For a PDOStatement object representing a scrollable cursor for which
the cursor_orientation parameter is set to
PDO::FETCH_ORI_ABS , this value specifies the
absolute number of the row in the result set that shall be fetched.
For a PDOStatement object representing a scrollable cursor for which
the cursor_orientation parameter is set to
PDO::FETCH_ORI_REL , this value specifies the
row to fetch relative to the cursor position before
PDOStatement->fetch() was called.
Return Values
The return value of this function on success depends on the fetch type. In
all cases, FALSE is returned on failure.
Examples
Example 1784. Fetching rows using different fetch styles
<?php
$sth = $dbh->prepare("SELECT name, colour FROM fruit"); $sth->execute();
/* Exercise PDOStatement::fetch styles */ print("PDO::FETCH_ASSOC: ");
print("Return next row as an array indexed by column name\n"); $result = $sth->fetch(PDO::FETCH_ASSOC); print_r($result);
print("\n");
print("PDO::FETCH_BOTH: ");
print("Return next row as an array indexed by both column name and number\n"); $result = $sth->fetch(PDO::FETCH_BOTH); print_r($result);
print("\n");
print("PDO::FETCH_LAZY: ");
print("Return next row as an anonymous object with column names as properties\n"); $result = $sth->fetch(PDO::FETCH_LAZY); print_r($result);
print("\n");
print("PDO::FETCH_OBJ: ");
print("Return next row as an anonymous object with column names as properties\n"); $result = $sth->fetch(PDO::FETCH_OBJ);
print $result->NAME;
print("\n"); ?>
The above example will output:
PDO::FETCH_ASSOC: Return next row as an array indexed by column name
Array
(
[NAME] => apple
[COLOUR] => red
)
PDO::FETCH_BOTH: Return next row as an array indexed by both column name and number
Array
(
[NAME] => banana
[0] => banana
[COLOUR] => yellow
[1] => yellow
)
PDO::FETCH_LAZY: Return next row as an anonymous object with column names as properties
PDORow Object
(
[NAME] => orange
[COLOUR] => orange
)
PDO::FETCH_OBJ: Return next row as an anonymous object with column names as properties
kiwi
Example 1785. Fetching rows with a scrollable cursor
<?php function readDataForwards($dbh) {
$sql = 'SELECT hand, won, bet FROM mynumbers ORDER BY BET';
try {
$stmt = $dbh->prepare($sql, array(PDO::ATTR_CURSOR => PDO::CURSOR_SCROLL));
$stmt->execute();
while ($row = $stmt->fetch(PDO::FETCH_NUM, PDO::FETCH_ORI_NEXT)) {
$data = $row[0] . "\t" . $row[1] . "\t" . $row[2] . "\n";
print $data;
}
$stmt = null;
}
catch (PDOException $e) {
print $e->getMessage();
}
}
function readDataBackwards($dbh) {
$sql = 'SELECT hand, won, bet FROM mynumbers ORDER BY bet';
try {
$stmt = $dbh->prepare($sql, array(PDO::ATTR_CURSOR => PDO::CURSOR_SCROLL));
$stmt->execute();
$row = $stmt->fetch(PDO::FETCH_NUM, PDO::FETCH_ORI_LAST);
do {
$data = $row[0] . "\t" . $row[1] . "\t" . $row[2] . "\n";
print $data;
} while ($row = $stmt->fetch(PDO::FETCH_NUM, PDO::FETCH_ORI_PRIOR));
$stmt = null;
}
catch (PDOException $e) {
print $e->getMessage();
}
}
print "Reading forwards:\n"; readDataForwards($conn);
print "Reading backwards:\n"; readDataBackwards($conn); ?>
The above example will output:
Reading forwards:
21 10 5
16 0 5
19 20 10
Reading backwards:
19 20 10
16 0 5
21 10 5
babna
When you do a SELECT query for one row, and want to check if it's there, you don't need to count the fetchAll() result, you can just check if $result->fetch() is true:
<?php
$bbnq = sprintf("SELECT login
FROM users
WHERE id = %u",27);
try
{ $req = $db_bbn->query($bbnq); }
catch (Exception $e)
{ bbnf_pdo_error($e,__FILE__,__LINE__); }
if ( $r = $req->fetch() )
{ echo "This query has a row result"; }
else
{ echo "This query has an empty result"; }
?>
dennis
Regarding the two previous notes - I downloaded the "latest CVS" a week ago for Windows and was surprised to notice that this issue is gone there, ie you don't have to close cursor before doing next query.
gerard van beek
If you to use a new instance of a class for a record you can use:
<?php
include_once("user.class");
$sth = $db->prepare("SELECT * FROM user WHERE id = 1");
/* create instance automatically */
$sth->setFetchMode( PDO::FETCH_CLASS, 'user');
$sth->execute();
$user = $sth->fetch( PDO::FETCH_CLASS );
$sth->closeCursor();
print ($user->id);
/* or create an instance yourself and use it */
$user= new user();
$sth->setFetchMode( PDO::FETCH_INTO, $user);
$sth->execute();
$user= $sth->fetch( PDO::FETCH_INTO );
$sth->closeCursor();
print ($user->id);
?>
marcini
Be careful with fetch() when you use prepared statements and MySQL (I don`t know how it is with other databases). Fetch won`t close cursor and won`t let you send any other query, even if your result set has only one row, .
If you use $statement->fetch(), you will also have to use $statement->closeCursor() afterwards, to be albe to execute another query.
Alternatively you can use $statement->fetchAll() without $statement->closeCursor().
redcube
as an alternative for marcini's note:
just clear the statement variable before you issue another query:
<?php
$stmt = $db->prepare('SELECT * FROM test');
// fetch only the first row
$row = $stmt->fetch(PDO::FETCH_ASSOC);
// clear the variable so its contents are destroyed (including the other rows in the result)
$stmt = null;
// now you can issue another query
$stmt = $db->prepare('SELECT * FROM test2');
?>
|
|