pg_field_prtlen
(PHP 4 >= 4.2.0, PHP 5)
pg_field_prtlen — Returns the printed length
Description
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 FALSE 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.
Note:
This function used to be called pg_fieldprtlen().
Parameters
-
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.
Return Values
The field printed length, or FALSE on error.
Examples
Example #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, $j) . " \n\n";
}
?>
The above example will output:
column 0 fieldname: author printed length: 6 characters storage length: -1 bytes field type: varchar column 1 fieldname: year printed length: 4 characters storage length: 2 bytes field type: int2 column 2 fieldname: title printed length: 24 characters storage length: -1 bytes field type: varchar
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Коментарии
mysql_field_len () function and more for postgres ...
problems ...
* pg_field_prtlen ... gives the actual size of the field back (it shows the count of the content allready inside the field - not the possible max-len)
* pg_filed_size ... can't be used for varchar or bpchar fields
...but there is a way to get the real-max-length of a field in postgreSQL via the system tables:
//returns an array with infos of every field in the table (name, type, length, size)
function SQLConstructFieldsInfo($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";
}
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.
Or even easier to keep things simple on fetching
SELECT a.attname AS name, t.typname AS type, a.attstorage AS i,
CASE WHEN a.attlen = -1 THEN a.atttypmod ELSE a.attlen END AS size
FROM pg_attribute a , pg_class c, pg_type t
WHERE c.relname = 'moo_members'
AND a.attrelid = c.oid AND a.atttypid = t.oid and a.attnum > 0 and not a.attisdropped