pg_field_name()

(PHP 4 >= 4.2.0, PHP 5, PHP 7)

返回字段的名字

说明

pg_field_name(resource $result,int $field_number): string

pg_field_name()返回给定 PostgreSQL$result资源中的$field_number所代表的字段名。字段编号从 0 开始。

Example #1 获取字段信息

<?php
    $dbconn = pg_connect("dbname=publisher") or die("Could not connect");
    $res = pg_query($dbconn, "select * from authors where author = 'Orwell'");
    $i = pg_num_fields($res);
    for ($j = 0; $j < $i; $j++) {
        echo "column $j\n";
        $fieldname = pg_field_name($res, $j);
        echo "fieldname: $fieldname\n";
        echo "printed length: ".pg_field_prtlen($res, $fieldname)." characters\n";
        echo "storage length: ".pg_field_size($res, $j)." bytes\n";
        echo "field type: ".pg_field_type($res, $j)." \n\n";
}
?>

上例的输出如下：

column 0
fieldname: author
printed length: 6 characters
storage length: -1 bytes
field type: varchar
column 1
fieldname: year
printed length: 4 characters
storage length: 2 bytes
field type: int2
column 2
fieldname: title
printed length: 24 characters
storage length: -1 bytes
field type: varchar

Note:

本函数以前的名字为pg_fieldname()。

参见pg_field_num()。

In fact you can extract the size of the varchar field, by simply sending the following query:
"select a.atttypmod,a.attrelid from pg_attribute as a, pg_class as c where c.relname='$table' AND a.attrelid=c.oid AND a.attname='$field'"
here is a simple function that does that:
function get_field_size($table, $field, $link) {
        
    $result = pg_query($link, "select a.atttypmod,a.attrelid from pg_attribute as a, pg_class as c where c.relname='$table' AND a.attrelid=c.oid AND a.attname='$field'");         
    
    $data = pg_fetch_object($result);
    
    return ($data->atttypmod - 4);    
  
}
returned value is a size of a given field (also varchar)

The pg_fieldname function only returns the unqualified name from the select statement. example:
select c.name, con.name from customer c, contacts con where con.customer_id = c.id;
pg_fieldname will return "name" for both fields instead of c.name and con.name.
This is a PostgreSQL limitation, not a PHP limitation.
if you need different field names you should use :
select c.name as customer_name, con.name as contact_name from customer c, contacts con where con.customer_id = c.id;
then pg_fieldname will return "customer_name" and "contact_name"