pg_field_table

(PHP 5 >= 5.2.0, PHP 7)

pg_field_table — Returns the name or oid of the tables field

说明

mixed pg_field_table ( resource $result , int $field_number [, bool $oid_only = false ] )

pg_field_table() returns the name of the table that field belongs to, or the table's oid if oid_only is TRUE.

参数

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.

返回值

On success either the fields table name or oid. Or, FALSE on failure.

范例

Example #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));
?>

以上例程的输出类似于：

foo
14379580

bool(false)

注释

Note:

Returning the oid is much faster than returning the table name because fetching the table name requires a query to the database system table.

参见

User Contributed Notes

strata_ranger at hotmail dot com 16-May-2009 08:11
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
?>