pg_field_prtlen
(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)
pg_field_prtlen — 返回打印的长度
说明
pg_field_prtlen() 返回 PostgreSQL result
中特定值的实际打印长度（字符数）。行编号从 0 开始。此函数将在出错时返回 false。
field_name_or_number 可以传递 int 或 string。如果它作为
int 传递，PHP 将其视为字段号，否则视为字段名。
请参阅 pg_field_name() 页面中给出的示例。
注意:
本函数以前的名字为 pg_fieldprtlen()。
参数
result-
PgSql\Result 实例，由 pg_query()、pg_query_params() 或者 pg_execute()（等）返回。
row-
结果中的行号。行从 0 向上编号。如果省略，则获取当前行。
返回值
字段打印的长度。
更新日志
| 版本 | 说明 |
|---|---|
| 8.3.0 |
row 现在可为 null。
|
| 8.1.0 |
现在 result 参数接受 PgSql\Result
实例，之前接受 resource。
|
示例
示例 #1 获取字段的信息
<?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";
}
?>以上示例会输出：
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
＋添加备注
用户贡献的备注 3 notes
gregm at gxsnmp dot org ¶
18 years ago
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.
djmaze@moocms ¶
17 years ago
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
r dot galovic at r-3 dot at ¶
19 years ago
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";
}备份地址：http://www.lvesu.com/blog/php/function.pg-field-prtlen.php