pg_fetch_result
(PHP 4 >= 4.2.0, PHP 5)
pg_fetch_result — Возвращает запись из результата запроса
Описание
pg_fetch_result() возвращает значение ячейки таблицы результата запроса.
Замечание:
Прежнее наименование функции: pg_result().
Список параметров
-
result -
Ресурс результата запроса PostgreSQL, возвращаемый функциями pg_query(), pg_query_params() или pg_execute() (в числе прочих).
-
row -
Номер выбираемой из результата запроса строки. Нумерация начинается с нуля. Если аргумент опущен, берется следующая по очереди строка.
-
field -
Имя или номер поля выбираемого значения. Поля нумеруются с нуля.
Возвращаемые значения
Логические значения возвращаются как "t" или "f".
Остальные типы, включая массивы, возвращаются в виде строк в стандартном
формате PostgreSQL, аналогично выводу программы psql.
Значения NULL базы данных преобразуются в PHP NULL.
FALSE, когда row превышает число строк в
результате запроса, и при прочих ошибках.
Примеры
Пример #1 Пример использования pg_fetch_result()
<?php
$db = pg_connect("dbname=users user=me") || die();
$res = pg_query($db, "SELECT 1 UNION ALL SELECT 2");
$val = pg_fetch_result($res, 1, 0);
echo "Первое поле во второй строчке результата это: ", $val, "\n";
?>
Результат выполнения данного примера:
Первое поле во второй строчке результата это: 2
Смотрите также
- pg_query() - Выполняет запрос
- pg_fetch_array() - Возвращает строку результата в виде массива
- PHP Руководство
- Функции по категориям
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Коментарии
Comment on boolean fields:
If you retrieve a boolean value from the PostgreSQL database, be aware that the value returned will be either the character 't' or the character 'f', not an integer. So, the statement
if (pg_fetch_result($rsRecords,0,'blnTrueFalseField')) {
echo "TRUE";
} else {
echo "FALSE";
}
will echo "TRUE" in either case (True or False stored in the field). In order to work as expected, do this instead:
if (pg_fetch_result($rsRecords,0,'blnTrueFalseField') == 't') {
echo "TRUE";
} else {
echo "FALSE";
}
Use can use pg_fetch_result when getting a value (like a smallint as in this example) returned by your stored procedure
<?php
$pgConnection = pg_connect("dbname=users user=me");
$userNameToCheckFor = "metal";
$result = pg_query($pgConnection, "SELECT howManyUsersHaveThisName('$userNameToCheckFor')");
$count = pg_fetch_result($result, 0, 'howManyUsersHaveThisName');
?>
In order to use upper case in pg_fetch_result column names, it is apparently necessary to include explicit quotation marks.
Thus when I do this sort of thing:
$res = pg_query(...);
$ncols = pg_num_fields($res);
for ($j = 0; $j < $ncols; ++$j) {
$colname[$j] = pg_field_name($res, $j);
$name = htmlspecialchars($colname[$j]);
print("Column $j name = \"$name\"\n");
$value = htmlspecialchars(pg_fetch_result($res, 0, $colname[$j]));
print("Column \"{$colname[$j]}\" value = \"$value\"\n");
}
I get this sort of thing:
[....]
Warning: pg_fetch_result() [function.pg-fetch-result]: Bad column offset specified in /.../view.php on line 247
Column 8 name = "VEC index"
Column "VEC index" value = ""
But if I change the $value line to this:
$value = htmlspecialchars(pg_fetch_result($res, 0, "\"$colname[$j]\""));
I get this:
[...]
Column 8 name = "VEC index"
Column "VEC index" value[0] = "47"
In my opinion, pg_fetch_result(...) should use the quotes already. In other words, this may be a bug in the PHP postgres library. It does not seem to be a documented feature of pg_fetch_result() although the postgresql manual documents it under "SQL syntax", "Lexical structure".
PHP version 5.1.4.
psql version 8.1.4.
See bug #33809 http://bugs.php.net/bug.php?id=33809
Whether this really is a bug or a feature is not clear.
However, it is probably best to always put your column names in extra quotes.
$res = pg_query(...);
$colname = pg_field_name($res, $j);
pg_fetch_result($res, $i, "\"$colname\"");
Please note that a very old bug (#76548) has been fixed in 7.2.8.
Previously, pg_fetch_result did not fetch the next row if $row was omitted.
It is now well the case, so bad use of the function can now cause some bugs in your codes.