pg_field_table
(PHP 5 >= 5.2.0)
pg_field_table — Returns the name or oid of the tables field
Описание
pg_field_table() returns the name of the table that field belongs to, or the table's oid if oid_only is TRUE.
Список параметров
- result
-
PostgreSQL query result resource, returned by pg_query(), pg_query_params() or pg_execute() (among others).
- field_number
-
Field number, starting from 0.
- oid_only
-
By default the tables name that field belongs to is returned but if oid_only is set to TRUE, then the oid will instead be returned.
Возвращаемые значения
On success either the fields table name or oid. Or, FALSE on failure.
Примеры
Пример #1 Getting table information about a field
<?php
$dbconn = pg_connect("dbname=publisher") or die("Could not connect");
$res = pg_query($dbconn, "SELECT bar FROM foo");
echo pg_field_table($res, 0);
echo pg_field_table($res, 0, true);
$res = pg_query($dbconn, "SELECT version()");
var_dump(pg_field_table($res, 0));
?>
Результатом выполнения данного примера будет что-то подобное:
foo 14379580 bool(false)
Примечания
Замечание: Returning the oid is much faster than returning the table name because fetching the table name requires a query to the database system table.
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Коментарии
pg_field_table is primarily useful for queries that involve joins between multiple tables, e.g:
<?php
$res = pg_query("SELECT table1.foo, table2.bar FROM table1 JOIN table2");
echo pg_field_table($res, 0); // Outputs 'table1'
echo pg_field_table($res, 1); // Outputs 'table2'
?>
However, be aware of a few easy 'gotchas':
1- If your query contains static values in its select-list, pg_field_table() will yield FALSE for those fields (because it was a static value, not one fetched from a table):
<?php
$res = pg_query("SELECT 'foo', bar FROM table");
echo pg_field_table($res, 0); // FALSE
echo pg_field_table($res, 1); // Outputs 'table'
?>
2- If you UNION two queries together from different tables, pg_field_table() will return FALSE for all fields:
<?php
$res = pg_query("(Select foo, bar from table1) UNION (Select foo, bar from table2)");
echo pg_field_table($res, 0); // FALSE
echo pg_field_table($res, 1); // FALSE
?>
this function return an OID even if your field comes from a view or a select but return FALSE if your field comes from an UNION select