PHP: pg_field_prtlen

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.

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

pg_field_prtlen

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";

}

pg_field_prtlen

Описание

Список параметров

Возвращаемые значения

Примеры

Смотрите также