DB_common::getCol()
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.
Parameter
-
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.
Return value
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
| Error code | Error message | Reason | Solution |
|---|---|---|---|
| DB_ERROR_INVALID | invalid | SQL statement 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 statement. |
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 chosen. | Check the DSN in connect(). |
| every other error code | Database specific error | Check the database related section of PHP Руководство 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-Statement for an Oracle database.) |
Замечание
This function can not be called statically.
Пример
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
)
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
)
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
)
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
)
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
)