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LXXXVII. PostgreSQL Functions
PostgreSQL database is Open Source product and available without
cost. Postgres, developed originally in the UC Berkeley Computer
Science Department, pioneered many of the object-relational concepts
now becoming available in some commercial databases. It provides
SQL92/SQL99 language support, transactions, referential integrity,
stored procedures and type extensibility. PostgreSQL is an open source
descendant of this original Berkeley code.
To use PostgreSQL support, you need PostgreSQL 6.5 or
later, PostgreSQL 7.0 or later to enable all PostgreSQL module
features. PostgreSQL supports many character encoding including
multibyte character encoding. The current version and more
information about PostgreSQL is available at
and
.
In order to enable PostgreSQL support,
--with-pgsql[=DIR] is required when you compile
PHP. DIR is the PostgreSQL base install directory, defaults to
/usr/local/pgsql. If shared object module is
available, PostgreSQL module may be loaded using
extension directive in php.ini or
dl()
function.
Chov�n� t�chto funkc� je ovlivn�no nastaven�m parametr� v php.ini.
Tabulka 1. PostgreSQL configuration options | Name | Default | Changeable |
|---|
| pgsql.allow_persistent | "1" | PHP_INI_SYSTEM | | pgsql.max_persistent | "-1" | PHP_INI_SYSTEM | | pgsql.max_links | "-1" | PHP_INI_SYSTEM | | pgsql.auto_reset_persistent | "0" | PHP_INI_SYSTEM | | pgsql.ignore_notice | "0" | PHP_INI_ALL | | pgsql.log_notice | "0" | PHP_INI_ALL |
For further details and definition of the PHP_INI_* constants see
ini_set().
Zde je stru�n� vysv�tlen�
konfigura�n�ch direktiv.
- pgsql.allow_persistent
boolean
Whether to allow persistent Postgres connections.
- pgsql.max_persistent
integer
The maximum number of persistent Postgres connections per
process.
- pgsql.max_links
integer
The maximum number of Postgres connections per process,
including persistent connections.
- pgsql.auto_reset_persistent
integer
Detect broken persistent links with pg_pconnect().
Needs a little overhead.
- pgsql.ignore_notice
integer
Whether or not to ignore PostgreSQL backend notices.
- pgsql.log_notice
integer
Whether or not to log PostgreSQL backends notice messages. The PHP
directive
pgsql.ignore_notice must be off in order to log notice
messages.
| Varov�n� |
Using the PostgreSQL module with PHP 4.0.6 is not recommended due to
a bug in the notice message handling code. Use 4.1.0 or later.
|
| Varov�n� |
PostgreSQL function names will be changed in 4.2.0 release to
confirm to current coding standards. Most of new names will have
additional underscores, e.g. pg_lo_open(). Some functions are
renamed to different name for consistency. e.g. pg_exec() to
pg_query(). Older names can be used in 4.2.0 and a few releases
from 4.2.0, but they may be deleted in the future.
Tabulka 2. Function names changed
The old pg_connect()/pg_pconnect()
syntax will be deprecated to support asynchronous connections in the
future. Please use a connection string for pg_connect()
and pg_pconnect().
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Not all functions are supported by all builds. It depends on your
libpq (The PostgreSQL C Client interface) version and how libpq is
compiled. If there is missing function, libpq does not support
the feature required for the function.
It is also important that you do not use an older libpq than the PostgreSQL
Server to which you will be connecting. If you use libpq older than PostgreSQL
Server expects, you may have problems.
Since version 6.3 (03/02/1998) PostgreSQL uses unix domain sockets
by default. TCP port will NOT be opened by default. A table is
shown below describing these new connection possibilities. This
socket will be found in /tmp/.s.PGSQL.5432.
This option can be enabled with the '-i' flag to
postmaster and its meaning is: "listen on
TCP/IP sockets as well as Unix domain sockets".
Tabulka 3. Postmaster and PHP | Postmaster | PHP | Status |
|---|
| postmaster & | pg_connect("dbname=MyDbName"); | OK | | postmaster -i & | pg_connect("dbname=MyDbName"); | OK | | postmaster & | pg_connect("host=localhost dbname=MyDbName"); |
Unable to connect to PostgreSQL server: connectDB() failed:
Is the postmaster running and accepting TCP/IP (with -i)
connection at 'localhost' on port '5432'? in
/path/to/file.php on line 20.
| | postmaster -i & | pg_connect("host=localhost dbname=MyDbName"); | OK |
A connection to PostgreSQL server can be established with the
following value pairs set in the command string: $conn =
pg_connect("host=myHost port=myPort tty=myTTY options=myOptions
dbname=myDB user=myUser password=myPassword ");
The previous syntax of:
$conn = pg_connect ("host", "port", "options", "tty", "dbname")
has been deprecated.
Environmental variables affect PostgreSQL server/client
behavior. For example, PostgreSQL module will lookup PGHOST
environment variable when the hostname is omitted in the connection
string. Supported environment variables are different from version
to version. Refer to PostgreSQL Programmer's Manual (libpq -
Environment Variables) for details.
Make sure you set environment variables for appropriate user. Use
$_ENV or getenv() to check
which environment variables are available to the current process.
P��klad 1. Setting default parameters PGHOST=pgsql.example.com
PGPORT=7890
PGDATABASE=web-system
PGUSER=web-user
PGPASSWORD=secret
PGDATESTYLE=ISO
PGTZ=JST
PGCLIENTENCODING=EUC-JP
export PGHOST PGPORT PGDATABASE PGUSER PGPASSWORD PGDATESTYLE PGTZ PGCLIENTENCODING |
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Pozn�mka:
PostgreSQL automatically folds all identifiers (e.g. table/column names)
to lower-case values. To get it to recognize upper-case values, you must
always wrap the identifier in quotes.
Tyto konstanty jsou definov�ny t�mto roz���en�m a budou k dispozici pouze
tehdy, bylo-li roz���en� zkompilov�no spole�n� s PHP nebo dynamicky zavedeno
za b�hu.
Starting with PostgreSQL 7.1.0, you can store up to 1GB into a
field of type text. In older versions, this was limited to the block
size (default was 8KB, maximum was 32KB, defined at compile time)
To use the large object (lo) interface, it is required to enclose
large object functions within a transaction block. A transaction
block starts with a SQL statement BEGIN and if
the transaction was valid ends with COMMIT or
END. If the transaction fails the transaction
should be closed with ROLLBACK or
ABORT.
P��klad 2. Using Large Objects |
<?php
$database = pg_connect("dbname=jacarta");
pg_query($database, "begin");
$oid = pg_lo_create($database);
echo "$oid\n";
$handle = pg_lo_open($database, $oid, "w");
echo "$handle\n";
pg_lo_write($handle, "large object data");
pg_lo_close($handle);
pg_query($database, "commit");
?>
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You should not close the connection to the PostgreSQL server
before closing the large object.
 add a note
User Contributed Notes
PostgreSQL Functions
adaml at mimuw edu pl
02-Oct-2004 01:07
Yes, PHP does support stored procedures
You have to add "select" before the name of the
procedure, just like that:
$result = pg_querry($conn, "SELECT procedure_x($aa)");
if a procedure returns a cursor you do something like that:
$result = pg_query($conn, "SELECT procedure_x('rcursor'); FETCH ALL IN rcursor");
24-Sep-2004 10:08
Does PHP support Postgresql stored procedures? Both selecting and storing stuff kinds?
raja shahed at christine nothdurfter dot com
16-Jul-2004 06:14
A very good tutorial for Windows users' is here Herr Johan Faxer Shows also how to install Cygwin.
74012 dot 2773 at compuserve dot com
02-Jul-2004 04:35
for just a list of tables, this works with postgresql-7.2.1:
function pg_list_tables($db) {
$sql = "select relname from pg_stat_user_tables order by relname;";
return pg_query($db, $sql);
}
abondi at ijk dot it
26-May-2004 12:11
I've found another function to mimic the following mysql list tables function () that's more useful for my target:
function pg_list_tables() {
$sql = "SELECT a.relname AS Name
FROM pg_class a, pg_user b
WHERE ( relkind = 'r') and relname !~ '^pg_' AND relname !~ '^sql_'
AND relname !~ '^xin[vx][0-9]+' AND b.usesysid = a.relowner
AND NOT (EXISTS (SELECT viewname FROM pg_views WHERE viewname=a.relname));";
return(pg_query($conn, $sql));
}
18-Mar-2004 01:50
I wrote some code that converts Postgres arrays to PHP arrays. I haven't done too much testing, but it seems to do the job for me.
/**
* A quick and dirty array grabber for postgres arrays. Not
* tested very well.
* @returns A PHP array.
**/
function toArray($pgArray){
if(strlen($pgArray) == 0){
return;
}
elseif($this->getChar($pgArray) == "," or $this->getChar($pgArray) == " "){
return $this->toArray(substr($pgArray, 1));
}
elseif($this->getChar($pgArray) == "{"){
//find the end of the array
$depth = 1;
for($i=1; $depth>0 && $i<strlen($pgArray); $i++){
if($this->getChar($pgArray, $i) == '\\'){
//skip escape chars
$i++;
next;
}
if($this->getChar($pgArray, $i) == "{"){
$depth++;
next;
}
if($this->getChar($pgArray, $i) == "}"){
$depth--;
next;
}
}
$arrayEnd = $i;
$first = substr($pgArray, 1, $arrayEnd - 2);
$second = substr($pgArray, $arrayEnd);
if($second == ""){
return $this->toArray($first);
}
$r[] = $this->toArray($first);
$r[] = $this->toArray($second);
return $r;
}
elseif($this->getChar($pgArray) == "\""){
//a quoted item
$depth = 1;
for($i=1; $depth && $i<strlen($pgArray); $i++){
if($this->getChar($pgArray, $i) == "\\"){
$i++;
next;
}
if($this->getChar($pgArray, $i) == "\""){
$depth--;
next;
}
}
$arrayEnd = $i;
$r[] = substr($pgArray, 1, $arrayEnd - 2);
$r = array_merge($r,
$this->toArray(substr($pgArray, $arrayEnd + 1)));
return $r;
}
else{
//an unquoted item
$depth = 1;
for($i=1; $depth && $i<strlen($pgArray); $i++){
if($this->getChar($pgArray, $i) == "\\"){
$i++;
next;
}
if($this->getChar($pgArray, $i) == ","){
$depth--;
next;
}
}
$arrayEnd = $i;
if($arrayEnd == strlen($pgArray)){
$r[] = $pgArray;
}
else{
$r[] = substr($pgArray, 0, $arrayEnd-1);
}
$r = array_merge($r,$this->toArray(substr($pgArray,
$arrayEnd)));
return $r;
}
}
function getChar($string, $pos=0){
return substr($string, $pos, 1);
}
fmonteiro11 at hotmail dot com
15-Jan-2004 06:50
Another good source of knowledge is
daniel at bichara dot com dot br
31-Dec-2002 01:04
Running RedHat Linux and Apache with suexec enabled you must include pgsql.so on each .php file using dl("pgsql.so") and remove "extension=pgsql.so" from php.ini, otherwise Apache (httpd) will not start.
anonymous at unknown dot com
29-Nov-2002 05:50
I just wanted to add to my previous post I've got the system up and running.
Environment: Windows XP, Apache 1.3.23, Php 4.3 RC2, PostGreSQL beta4 native windows build
Installation was fairly easy:
1. read the readme.txt
2. edit the setenv.bat as described in readme
3. run 'initdb'
all execs are in /bin
help is accessed like <command> --help
4. Start the psql deamon - you may want to create a batch file like
'D:\postgres_beta4\bin\postmaster -h localhost -D D:/postgres_beta4/data'
--deamon should be up and running now--
You can login into a shell from a console like
'psql -h localhost -d <username>'
You must load the postgresql extension by editing the php.ini and restarting apache in order to access psql with php.
And one final not: when running
$dbconn = pg_connect ("host=localhost port=5432 dbname=$dbname user=$user");
remember that $user and or $dbname is CASESENSITIVE.
Oh yeah, I created the data dir manually - don't know whether that was necessary
Grtz Vargo
amk at eight13 dot com
27-Nov-2002 07:36
The list of postgresql function name changes is missing pg_errormessage being changed to pg_last_error.
swm at php dot net
22-Aug-2002 03:49
My talk on PHP and PostgreSQL which I presented at O'Reilly OSCON 2002 is now online.
mystran at wasteland dot pp dot htv dot fi
04-Feb-2002 03:46
Nice to know fact that I didn't find documented here.
PHP will return values of PostgreSQL boolean datatype as single character strings "t" and "f", not PHP true and false.
[Editor's Note]
't' or 'f' is valid boolean expression for PostgreSQL.
All values from PostgreSQL are strings, since PostgreSQL integer, float may be much larger than PHP's native int, double can handle. PostgreSQL array is not supported.
saberit at home dot com
15-Sep-2001 09:11
I tried compiling PHP from source with PostgreSQL support (./configure --with-pgsql=/usr/local/pgsql) and ran into a bunch of problems when trying to 'make'. The problem was that some of the PostgreSQL headers were not installed by default when I installed PostgreSQL from source. When installing PostgreSQL make sure you 'make install-all-headers' after you 'make install'.
hubert at hubertmuller dot com
09-Jul-2001 11:36
The best way to find the separated list of tables, sequences, keys etc is:
SELECT relname FROM pg_class WHERE relkind='<value>' AND relname !~ '^pg_';
<value> takes:
i for keys,
r for relations,
S for sequences
Note that all tables names that begins with 'pg_' are PostgreSQL internal tables (this explain why I use AND relname !~ '^pg_' condition).
passion at monkey dot org
28-Jun-2001 01:53
I've tried to mimic the following mysql database connection functions for postgres.
These are assuming that you're passing in $link as the result from pg_connect:
function pg_list_dbs($link)
{
$sql = 'SELECT datname FROM pg_database';
return (pg_query($link, $sql));
}
function pg_list_tables($link)
{
$sql = "SELECT relname FROM pg_class WHERE relname !~ '^pg_'";
return (pg_query($link, $sql));
}
!spamcraig at ahdore dot com
15-Apr-2001 08:11
If you want to extract data from select statements, you need to store the result index, and then apply pg_result to that value. Basically, do this
$resultIdx = pg_query ($database, "select * from tablename");
$mySelect = pg_fetch_result($resultIdx, 0, 0); // gets column 0 of tuple 0
echo("My select: [".$mySelect."]");
I'm new to php and had to do some fiddling around to work this out. It's reasonably elementary, but not demonstrated by the examples on these pages. Hopefully it will come in useful to someone else.
jdb30 at cornell.edu
06-Dec-2000 08:08
For further reading on PostgreSQL, see:
bleach at chek dot com
02-Mar-2000 08:36
If you want to see all the objects in a database, you can find that information in the pg_class table. <BR>
SELECT * FROM pg_class;<BR>
Now this is going to be kind of long and complex, to see how psql command handles the \d and other things. use the syntax. psql -E <Database>, ie psql -E mydatabase <BR>
What this will do is show the SQL command used for everything. So when you type a \d or something, it shows the SQL query used for the result.
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posix_uname
