PostgreSQL 函数
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pg_field_prtlen

(PHP 4 >= 4.2.0, PHP 5)

pg_field_prtlen — 返回打印出来的长度

说明

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

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()。

PostgreSQL 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: 返回打印出来的长度

用户评论:

djmaze@moocms (25-Aug-2007 01:01)

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

gregm at gxsnmp dot org (12-Feb-2007 04:11)

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 09:54)

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";
}