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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()]])

Descripción

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

Parámetro

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.

Valor devuelto

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.

Lanza

Tabla 35-1. Posibles valores de PEAR_Error

Error codeError messageReasonSolution
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.)

Nota

Esta función no puede ser llamada estáticamente.

Ejemplo

Ejemplo 35-1. Using getCol() 


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

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

print_r($data);
?>

Output: 

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

Ejemplo 35-2. 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 (PEAR::isError($data)) {
    die($data->getMessage());
}

print_r($data);
?>

Output: 

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

Ejemplo 35-3. 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 (PEAR::isError($data)) {
    die($data->getMessage());
}

print_r($data);
?>

Output: 

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

Ejemplo 35-4. 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 (PEAR::isError($data)) {
    die($data->getMessage());
}

print_r($data);
?>

Output: 

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

Ejemplo 35-5. 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 (PEAR::isError($data)) {
    die($data->getMessage());
}

print_r($data);
?>

Output: 

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

Ver

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

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