PostgreSQL 函数
在线手册：中文 英文
PHP手册

pg_query

(PHP 4 >= 4.2.0, PHP 5)

pg_query — 执行查询

说明

resource pg_query ( resource $connection , string $query )

pg_query() 在查询可以执行时返回查询结果资源号。如果查询失败或者提供的连接号无效则返回 FALSE。如果连接号有效，则可以用 pg_last_error() 函数来提取详细的错误信息。pg_query() 发送一条 SQL 语句到 connection 资源指定的 PostgreSQL 数据库。connection 必须是由 pg_connect() 或 pg_pconnect() 返回的合法连接号。本函数返回值是一个其它 PostgreSQL 函数例如 pg_fetch_array() 可以用来访问查询结果的查询结果资源号。

Note: connection 是 pg_query() 中的可选参数。如果没有指定 connection，则使用默认连接。默认连接是 pg_connect() 或 pg_pconnect() 所打开的最后一个连接。 尽管 connection 参数可以省略，但不推荐这样做。因为这样可能会导致很难发现脚本中的错误。

Note:

本函数以前的名字为 pg_exec()。pg_exec() 函数为了兼容性的原因仍然可以使用，但是鼓励用户使用新的名字。

参见 pg_connect()，pg_pconnect()，pg_fetch_array()，pg_fetch_object()，pg_num_rows() 和 pg_affected_rows()。

PostgreSQL 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: 执行查询

用户评论:

MomAlwaysLikedMeBest at hotmail (26-Apr-2011 07:42)

Transactions can be accomplished using the following syntax:

<?php
pg_query($db, "BEGIN WORK");

// Some insert/update/delete queries.
$res=pg_query($db, "INSERT INTO customers (customer_id) VALUES ('$customer_id')");

// Verify and end the transaction as appropriate.
if (!$res) {
    pg_query($db, "ROLLBACK");
} else {
    pg_query($db, "COMMIT");
}
?>

sd at dicksonlife dot com (14-Sep-2006 08:40)

Took me a while to track this down so I thought it might be useful for others:

If you use stored procedures and need to get result sets back from them:

function dbquery($link,$query){
  pg_query($link,"BEGIN;");
  $tr=pg_query($link,$query);
  $r=pg_fetch_row($tr);
  $name=$r[0];
  $rs=pg_query($link,"FETCH ALL IN \"" . $name . "\";");
  pg_query($link,"END;");
  return $rs;
}

(Error checking removed for clarity)

zoli at makettinfo.hu (21-May-2006 04:07)

It would be better this way:

<?php
  $result=pg_query($conn, "SELECT COUNT(*) AS rows FROM x WHERE a=b;");
  if  (!$result) {
   echo "query did not execute";
  }
  if ($line = pg_fetch_assoc($result)) {
    if ($line['rows'] == 0) {
     echo "0 records"
    }
  }
  else {
   while ($row = pg_fetch_array($result)) {
     //do stuff with $row
   }
  }
?>

This solution doesn't raise the load of the system with the move of matching rows (perhaps 0,1, perhaps 100, 1000, ... rows)

mankyd (13-May-2006 03:21)

There was a typo in the code that I posted:

<?php
  $result=pg_query($conn, "SELECT * FROM x WHERE a=b;");
  if  (!$result) {
   echo "query did not execute";
  }
  if (pg_num_rows($result) == 0) {
   echo "0 records"
  }
  else {
   while ($row = pg_fetch_array($result)) {
     //do stuff with $row
   }
  }
?>

mankyd (13-May-2006 02:56)

Improving upon what jsuzuki said:

It's probably better to use pg_num_rows() to see if no rows were returned, as that leaves the resultset cursor pointed to the first row so you can use it in a loop.

Example:

<?php
  $result=pg_query($conn, "SELECT * FROM x WHERE a=b;");
  if  (!$result) {
   echo "query did not execute";
  }
  if (pg_num_rows($result) == 0) {
   echo "0 records"
  }
  else {
    while ($row = pg_fetch_array($result) {
      //do stuff with $row
    }
  }
?>

I, personally, also find it more readable.

jsuzuki at spamcop dot net (27-Nov-2005 01:58)

expanding on the note left by "cmoore" -

To check to see if the recordset returned no records,

<?php
  $result=pg_query($conn, "SELECT * FROM x WHERE a=b;");
  if  (!$result) {
    echo "query did not execute";
  }
  $rs = pg_fetch_assoc($result);
  if (!$rs) {
    echo "0 records"
  }
?>

-jack

Jan-Willem Regeer (28-Sep-2005 12:58)

In reply to david dot bouriaud at ac-rouen dot fr:

All it is doing is internal caching. How can that be dangerous. If you are going to be deleting records after you have closed the connection it is your problem to make sure you have the latest and greatest records, and not some cached ones. Considering you are writing the script I don't see why it is a problem, you know what you are doing in the script, so it is quite useless for PHP to invalidate the cache, when that could be done upon exiting the script, which would mean there was less time spent cleaning out the cache when it counts most (when returning data to the user).

cmoore (05-Sep-2005 07:20)

One thing to note that wasn't obvious to me at first.  If your query returns zero rows, that is not a "failed" query.  So the following is wrong:
  $result=pg_query($conn, "SELECT * FROM x WHERE a=b;");
  if  (!$result) {
    echo "No a=b in x\n";
  }

pg_query returns FALSE if the query can not be executed for some reason.  If the query is executed but returns zero rows then you get back a resul with no rows.

Akbar (01-Dec-2004 04:07)

Use pg_query to call your stored procedures, and use pg_fetch_result when getting a value (like a smallint as in this example) returned by your stored procedure.

<?php
$pgConnection = pg_connect("dbname=users user=me");

$userNameToCheckFor = "metal";

$result = pg_query($pgConnection, "SELECT howManyUsersHaveThisName('$userNameToCheckFor')");

$count = pg_fetch_result($result, 0, 'howManyUsersHaveThisName');
?>

yoshinariatsuo at yahoo dot com (23-Apr-2003 07:59)

create table from pg_query results.. hope it helps newbies...
function table_create($result)
{
    $numrows = pg_num_rows($result);
    $fnum = pg_num_fields($result);

    echo "<table border width='100%'>";
    echo "<tr>";

    for ($x = 0; $x < $fnum; $x++) {
        echo "<td><b>";
        echo strtoupper(pg_field_name($result, $x));
        echo "</b></td>";
    }

    echo "</tr>";

    for ($i = 0; $i < $numrows; $i++) {
        $row = pg_fetch_object($result, $i);
        echo "<tr align='center'>";
        for ($x = 0; $x < $fnum; $x++) {
    $fieldname = pg_field_name($result, $x);
    echo "<td>";
    echo $row->$fieldname;
    echo "</td>";
        }
        echo"</tr>";
    }
    echo "</table>";
   
    return 0;
}

mentat at azsoft dot pl (14-Oct-2002 01:16)

$GLOBALS["PG_CONNECT"]=pg_connect(...);
....

function query ($sqlQuery,$var=0) {
   if (!$GLOBALS["PG_CONNECT"]) return 0;
   $lev=error_reporting (8); //NO WARRING!!
   $result=pg_query ($sqlQuery);
   error_reporting ($lev); //DEFAULT!!
   if (strlen ($r=pg_last_error ($GLOBALS["PG_CONNECT"]))) {
      if ($var) {
        echo "<p color=\"red\">ERROR:<pre>";
        echo $sqlQuery;
        echo "</pre>";
        echo $r;
        echo "&lt/p>";
      }
      close_db ();
      return 0;
   }
   return $result;
}

hierophantNOSPAM at pcisys dot net (17-Jun-2002 08:50)

Regarding david.bouriaud@ac-rouen.fr:
You misunderstand SQL. When a query is issued, results applicable at the time of the query are returned to the application (i.e. PHP). There is no further reference to the database required. Thus, all of the pg_fetch_* functions are acting on an internal data storage, NOT the database itself. This is because SQL does not have a concept of sets, or of state (except in limited circumstances provided by transactions). However, if you use a cursor instead, fetching only one record at a time, you may get an error if you delete the table. If you don't, it is an issue with Postgres, not PHP.

jvarner at dsrglobal dot com (10-May-2002 11:18)

That's why your code should never assume it has the very latest data unless it locks it.

david dot bouriaud at ac-rouen dot fr (07-May-2002 06:54)

Hi to all !
It seems that the old pg_exec function does not do what it is expected to.
In the doc, it is said that it returns a resource identifier on the successful querry that was send to the backend.
It seems to me that it is more than a resource identifier.
Follow the example :

<?php
$ConnId = pg_connect ("blablabla");
$ResId = pg_exec ("select * from table", $ConnId);
pg_close ($ConnId);
$row = pg_fetch_array ($ResId, 4);
?>

I closed the connection voluntarily before the pg_fetch_array. It WORKS !

Now, imagine the following script :
<?php
$ConnId = pg_connect ("blablabla");
$ResId = pg_exec ("select * from table", $ConnId);
pg_close ($ConnId);
system ("psql base -c delete from table");
$row = pg_fetch_array ($ResId, 4);
?>
See how it could be harmful !!!! I think that the coders have done this for performances reasons, but it is not the right way do do so !!!