pg_field_prtlen()

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

返回打印出来的长度

说明

pg_field_prtlen(resource $result,int $row_number,string $field_name): int

pg_field_prtlen()返回 PostgreSQL$result中得到的值实际上打印出来的长度（字符数）。行编号从 0 开始。如果出错本函数返回-1。

例子参见pg_field_name()页。

Note:

本函数以前的名字为pg_field_prtlen()。

参见pg_field_size()。

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

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";
}