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	Last updated: Sun, 16 May 2004

DB_common::getCol()

DB_common::getCol() -- Runs a query and returns the data from a single column

Synopsis

array &getCol (string $query [, mixed $col = 0 [, mixed $params = array()]])

Описание

Runs the query provided and puts the first column of data into an array then frees the result set.

Параметр

string $query

the SQL query or the statement to prepare

mixed $col

which column to return (integer [column number, starting at 0] or string [column name])

mixed $params

array, string or numeric data to be added to the prepared statement. Quantity of items passed must match quantity of placeholders in the prepared statement: meaning 1 placeholder for non-array parameters or 1 placeholder per array element.

If supplied, prepare()/ execute() is used.

Возвращаемое значение

array - an ordered array containing data from a result set column or a DB_Error object on failure. The array's index starts at 0.

Throws

Таблица 22-1. Возможные значения PEAR_Error

Error code	Error message	Reason	Solution
`DB_ERROR_INVALID`	invalid	SQL statment for preparing is not valid.	See the prepare() documentation, if you want to use a SQL statemt using placeholders.
`DB_ERROR_MISMATCH`	mismatch	Quantity of parameters didn't match quantity of placeholders in the prepared statment.	Check that the number of placeholders in the prepare() statement passed to `$query` equals the count of entries passed to `$params`.
`DB_ERROR_NOSUCHFIELD`	no such field	Invalid column number/name passed to `$col`	Use a column number or name that exists in the query result.
`DB_ERROR_NODBSELECTED`	no database selected	No database was choosen.	Check the DSN in connect().
every other error code		Database specific error	Check the database related section of PHP Manual to detect the reason for this error. In most cases a malformed SQL statement is the cause of the error. (Ie. using LIMIT in a SQL-Statment for an Oracle database.)

Заметка

Эта функция не должна вызываться статически.

Пример

Пример 22-1. Using getCol()


<?php
// Once you have a valid DB object named $db...
$data =& $db->getCol('SELECT cf, df FROM foo');

if (DB::isError($data)) {
    die($data->getMessage());
}

print_r($data);
?>

Output:

Array
(
    [0] => Juan
    [1] => Kyu
)

Пример 22-2. Using getCol() to retrieve a numerically specified column


<?php
// Once you have a valid DB object named $db...
$data =& $db->getCol('SELECT cf, df FROM foo', 1);

if (DB::isError($data)) {
    die($data->getMessage());
}

print_r($data);
?>

Output:

Array
(
    [0] => 1991-01-11 21:31:41
    [1] => 1992-02-12 22:32:42
)

Пример 22-3. Using getCol() to retrieve a named column


<?php
// Once you have a valid DB object named $db...
$data =& $db->getCol('SELECT cf, df FROM foo', 'df');

if (DB::isError($data)) {
    die($data->getMessage());
}

print_r($data);
?>

Output:

Array
(
    [0] => 1991-01-11 21:31:41
    [1] => 1992-02-12 22:32:42
)

Пример 22-4. Using getCol() in prepare/execute mode with one placeholder


<?php
// Once you have a valid DB object named $db...
$data =& $db->getCol('SELECT cf, df FROM foo WHERE nf = ?',
        'df', 5);

if (DB::isError($data)) {
    die($data->getMessage());
}

print_r($data);
?>

Output:

Array
(
    [0] => 1991-01-11 21:31:41
)

Пример 22-5. Using getCol() in prepare/execute mode with two placeholders


<?php
// Once you have a valid DB object named $db...
$data =& $db->getCol('SELECT cf, df FROM foo WHERE nf IN (?, ?)',
        'df', array(5, 10));

if (DB::isError($data)) {
    die($data->getMessage());
}

print_r($data);
?>

Output:

Array
(
    [0] => 1991-01-11 21:31:41
    [1] => 1992-02-12 22:32:42
)

См. также

getOne(), getRow(), getAssoc(), getAll(), query(), "Intro - Prepare & Execute"

DB_common::getAssoc() (Previous)

(Next) DB_common::getListOf()

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Last updated: Sun, 16 May 2004