pg_field_name

(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

pg_field_name — 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()。

User Contributed Notes

12-Aug-2004 10:01


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)

ccasal at compuserve dot com 12-Jan-2001 11:51


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"