PHP: pg_field_prtlen - Manual

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Last updated: Sat, 27 Jan 2007

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# pg_field_prtlen

(PHP 4 >= 4.2.0, PHP 5)

pg_field_prtlen -- Returns the printed length

## Описание

int pg_field_prtlen ( resource result, int row_number, mixed field_name_or_number )
int pg_field_prtlen ( resource result, mixed field_name_or_number )

pg_field_prtlen() returns the actual printed length (number of characters) of a specific value in a PostgreSQL `result`. Row numbering starts at 0. This function will return -1 on an error.

`field_name_or_number` can be passed either as an integer or as a string. If it is passed as an integer, PHP recognises it as the field number, otherwise as field name.

See the example given at the pg_field_name() page.

> Замечание: This function used to be called pg_fieldprtlen().

## Список параметров

`result`

  PostgreSQL query result resource, returned by pg_query(), pg_query_params() or pg_execute() (among others).

`row`

  Row number in result. Rows are numbered from 0 upwards. If omitted, current row is fetched.

## Возвращаемые значения

The field printed length, or `FALSE` on error.

## Примеры

Пример 1. Getting information about fields

`<?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";
}
?>`

Результат выполнения данного примера:

    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

## Смотрите также

pg_field_size()

add a note User Contributed Notes
pg_field_prtlen
gregm at gxsnmp dot org
12-Feb-2007 08:11
`If you update the query to this:
$s = "SELECT a.attname AS name, t.typname AS type, a.attlen AS size, a.atttypmod AS len, a.attstorage AS i
FROM pg_attribute a , pg_class c, pg_type t
WHERE c.relname = '$TABLE'
AND a.attrelid = c.oid AND a.atttypid = t.oid and a.attnum > 0 and not a.attisdropped";
You get postgres to filter out the 'postgres' columns and get only your columns back.`
r dot galovic at r-3 dot at
18-Apr-2005 01:54
`mysql_field_len () function and more for postgres ...
problems ...
* pg_field_prtlen ... gives the actual size of the field back (it shows the count of the content allready inside the field - not the possible max-len)
* pg_filed_size ... can't be used for varchar or bpchar fields
...but there is a way to get the real-max-length of a field in postgreSQL via the system tables:
//returns an array with infos of every field in the table (name, type, length, size)
function SQLConstructFieldsInfo($TABLE, $DBCON)
{
$s="SELECT a.attname AS name, t.typname AS type, a.attlen AS size, a.atttypmod AS len, a.attstorage AS i
FROM pg_attribute a , pg_class c, pg_type t
WHERE c.relname = '$TABLE'
AND a.attrelid = c.oid AND a.atttypid = t.oid";
if ($r = pg_query($DBCON,$s))
{
$i=0;
while ($q = pg_fetch_assoc($r))
{
$a[$i]["type"]=$q["type"];
$a[$i]["name"]=$q["name"];
if($q["len"]<0 && $q["i"]!="x")
{
// in case of digits if needed ... (+1 for negative values)
$a[$i]["len"]=(strlen(pow(2,($q["size"]*8)))+1);
}
else
{
$a[$i]["len"]=$q["len"];
}
$a[$i]["size"]=$q["size"];
$i++;
}
return $a;
}
return null;
}
// usage
$DBCON=pg_connect("host=YOUR-HOST port=YOUR-PORT dbname=YOUR-DB user=YOUR-USER password=YOUR-PASS");
$TABLE="YOUR-TABLENAME";
$RET=SQLConstructFieldsInfo($TABLE, $DBCON);
$j = count($RET);
for ($i=0; $i < $j; $i++)
{
echo "<br>$i name=".$RET[$i]["name"]." type=".$RET[$i]["type"]." length=".$RET[$i]["len"]." size=".$RET[$i]["size"]." bytes";
}`
add a note
pg_field_size pg_field_num

Last updated: Sat, 27 Jan 2007
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