pg_send_query

说明

bool pg_send_query ( resource connection, string query )

bool pg_send_query ( string query )

pg_send_query() 向 connection 连接发送异步查询。和 pg_query() 不同，它可以向 PostgreSQL 发送多个查询并用 pg_get_result() 依次得到结果。当执行查询时脚本的执行不会被锁定。用 pg_connection_busy() 来检查连接连接是否为忙（即查询正在执行中）。调用 pg_cancel_query() 则有可能取消查询。

尽管用户可以一次发送多个查询，但用户不能通过正忙的连接发送多个查询。如果向正忙的连接发送了查询，则会等待上一条查询结束并丢弃所有结果。

例子 1. 异步查询
<?php $dbconn = pg_connect("dbname=publisher") or die("Could not connect"); if (!pg_connection_busy($dbconn)) { pg_send_query($dbconn,"select * from authors; select count(*) from authors;"); } $res1 = pg_get_result($dbconn); echo "First call to pg_get_result(): $res1\n"; $rows1 = pg_num_rows($res1); echo "$res1 has $rows1 records\n\n"; $res2 = pg_get_result($dbconn); echo "second call to pg_get_result(): $res2\n"; $rows2 = pg_num_rows($res2); echo "$res2 has $rows2 records\n"; ?>
上例输出如下：
first call to pg_get_result(): Resource id #3 Resource id #3 has 3 records second call to pg_get_result(): Resource id #4 Resource id #4 has 1 records

参见 pg_query()，pg_cancel_query()，pg_get_result() 和 pg_connection_busy()。

add a note User Contributed Notes

vincentdephily
29-Nov-2005 09:25


Note that if you send a query without calling pg_get_result() for the previous one (supposing it has finished and the connection is not busy), the previous query will get discarded.



See for yourself (tested on php4.4.0, postgres8.0.4, Linux/FreeBSD) :

<?

$conn = pg_connect("dbname=template1 host=localhost user=pgsql");

if ($conn === FALSE)

  exit("Can't connect to db");



$q = array();

// send some queries

foreach (range(0, 500) as $i)

  stack_query($q, $conn, "SELECT 'query $i' AS str;");

// receive them

while (true)

  {

    $left = stack_query($q, $conn);

    echo "$left left... ";

    $result = pg_get_result($conn);

    if ($left == 0 && $result === FALSE)

      break;

    $row = pg_fetch_assoc($result);

    // depending on race conditions, you wont get all your original queries here.

    echo "got $row[str]\n";

  }



function stack_query(&$queries, $conn, $sql = FALSE)

{

  if ($sql !== FALSE)

    $queries[] = $sql;

  while (count($queries) && !pg_connection_busy($conn))

    pg_send_query($conn, array_shift($queries));

  return count($queries) + (pg_connection_busy($conn) ? 1 : 0);

}

?>



You will have to write a higher level of abstraction if you want a "send all queries now, receive them later" behaviour.

Likeyouover others at hotmail dot com
03-Sep-2003 05:29


<?php

// --------- OPEN CONN ---



   $conn = pg_connect("host='127.0.0.1' dbname='test' user='usertest' password='passtest'");



// --------- OPEN FILE ---



   $fp = fopen('logo.gif', "r");

   $buffer = fread($fp, filesize('logo.gif'));

   fclose($fp);



// --------- CREATE - INSERT OID ---



   pg_exec($conn, "begin");



   $oid = pg_locreate($conn);



   $rs = pg_exec($conn,"INSERT INTO test(tipo, images) VALUES('A1', $oid);");

   $handle = pg_loopen ($conn, $oid, "w");



   pg_lowrite ($handle, $buffer);

   pg_loclose ($handle);



   pg_exec($conn, "commit");



// --------- OPEN - INSERT OID ---



   $rs = pg_exec($conn, "SELECT images FROM test WHERE tipo = 'A1';");

   $row = pg_fetch_row($rs, 0);



   pg_exec($conn, "begin");

   $loid = pg_loopen($conn, $row[0], "r");



   header("Content-type: image/gif");



   pg_loreadall($loid);

   pg_loclose($loid);



   pg_exec ($conn, "commit");



// --------- UNLINK OID ---



   pg_exec($conn, "begin");



   $loid = $row[0];

   pg_lounlink($conn, $loid);



   pg_exec ($conn, "commit");



// --------- DELETE OID ---



   pg_exec($conn, "DELETE FROM test WHERE tipo = 'A1';");



// --------- CLOSE CONN ---



   pg_close();

?>

Mikewithme at yahoo dot com
03-Sep-2003 05:28


Due to a bug, OLD API does not available with PHP 4.2.0 and 4.2.1.



PHP 4.2.2 will support OLD API again and will be kept long enough.



New API will be available PHP 4.2.0 to later versions. 

yohgaki at php dot net

19-Jun-2002 04:00 

Due to a bug, PHP 4.2.0 and 4.2.1 does not support pg_lo_import() old API. It's fixed in PHP 4.2.2.



BTW, new API will be always available from PHP 4.2.0 to later versions. Older API will be kept long enough, also. 

ceco at noxis dot net

15-May-2002 09:08 

it works for me (php-4.2.1)



not like this



int pg_lo_import ( string pathname [, resource connection])



but 

int pg_lo_import ( resource connection, string pathname )



don't know the reason

Ron Howard
05-Jan-2003 11:20


If there is an error in one of your queries, the queries following it will not get executed, and there will *not* be an error message displayed. The only way I can think of to determine if an SQL error happened is to use pg_trace.



Example:



pg_send_query($connection,

    "SELECT id FROM users;

    SELECT * FROM customers;

     [INVALID-SQL-STATEMENT];

    SELECT name FROM countries;");



while ($result = pg_get_result($connection))

    $results[] = $result;



The $results array will only have two items in it.

add a note