PostgreSQL 函数
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pg_escape_bytea

(PHP 4 >= 4.2.0, PHP 5)

pg_escape_bytea — 转义 bytea 类型的二进制数据

说明

string pg_escape_bytea ( string $data )

pg_escape_bytea() 转义 bytea 数据类型的二进制字符串，返回转义后的字符串。

Note:

当对 bytea 类型字段进行 SELECT 操作时，PostgreSQL 返回前导 \ 的八进制字节值（例如 \032）。用户需要自己将结果转换为二进制格式。

本函数需要 PostgreSQL 7.2 或以上版本。在 PostgreSQL 7.2.0 和 7.2.1 版中，如果使用了多字节支持，bytea 类型必须被强制转换。例如 INSERT INTO test_table (image) VALUES ('$image_escaped'::bytea);。PostgreSQL 7.2.2 或以上版本不需要强制转换。异常情况是当客户端和后端字符编码不匹配时，可能会有多字节流错误。用户必须强制转换 bytea 以避免此错误。

参见 pg_unescape_bytea() 和 pg_escape_string()。

PostgreSQL 函数
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PHP手册
PHP手册 - N: 转义 bytea 类型的二进制数据

用户评论:

Mike-RaWare (08-Jul-2010 10:03)

To prevent any problems with encoding you could use hexadecimal or base64 input to save and retrieve data to the database:

<?php
  // Connect to the database
  $dbconn = pg_connect( 'dbname=foo' );
 
  // Read in a binary file
  $data = file_get_contents( 'image1.jpg' );
 
  // Escape the binary data
  $escaped = bin2hex( $data );
 
  // Insert it into the database
  pg_query( "INSERT INTO gallery (name, data) VALUES ('Pine trees', decode('{$escaped}' , 'hex'))" );

  // Get the bytea data
  $res = pg_query("SELECT encode(data, 'base64') AS data FROM gallery WHERE name='Pine trees'"); 
  $raw = pg_fetch_result($res, 'data');
 
  // Convert to binary and send to the browser
  header('Content-type: image/jpeg');
  echo base64_decode($raw);
?>

gglockner AT NOSPAMdwaffler DOT com (17-Jul-2009 10:13)

If you're getting errors about nonstandard use of \\ in a string literal, then you need to escape the encoded bytea as follows:

<?php
$escaped = pg_escape_bytea($data);
pg_query("INSERT INTO gallery (name, data) VALUES ('Pine trees', E'$escaped'::bytea)");
?>

ynzhang from lakeheadu of ca (18-Feb-2009 09:44)

The reason pg_unescape_bytea() do not exactly reproduce the binary data created by pg_escape_bytea() is because the backslash \ and single quote ' are double escaped by the pg_escape_bytea() function. This will lead to image seems corrupted when retrieve from the bytea field. The proper way to escape&unescape a binary string into a PG bytea field as follow:

<?php
$escaped_data = str_replace(array("\\\\", "''"), array("\\", "'"), pg_escape_bytea($data));
/* and later unescape the escaped data from the bytea field with following to get the original binary data */

$original_data = pg_unescape_bytea($escaped_data));
?>

more details at: http://archives.postgresql.org/pgsql-php/2007-02/msg00014.php

Mocha (08-Aug-2003 01:20)

to unescape_bytea use stripcslashes(). If you need to escape bytea and don't have pg_escape_bytea() function then use:

<?php
function escByteA($binData) {
  /**
   * \134 = 92 = backslash, \000 = 00 = NULL, \047 = 39 = Single Quote
   *
   * str_replace() replaces the searches array in order. Therefore, we must
   * process the 'backslash' character first. If we process it last, it'll
   * replace all the escaped backslashes from the other searches that came
   * before.
   */
  $search = array(chr(92), chr(0), chr(39));
  $replace = array('\\\134', '\\\000', '\\\047');
  $binData = str_replace($search, $replace, $binData);
  return $binData;
  //echo "<pre>$binData</pre>";
  //exit;
}
?>

php at tobias dot olsson dot be (17-Aug-2002 05:56)

if you need to change back bytea from the db to normal data, this will do that:

<?php
function pg_unescape_bytea($bytea) {
return eval("return \"".str_replace('$', '\\$', str_replace('"', '\\"', $bytea))."\";");
}

// use like this
$rs = pg_query($conn, "SELECT image from images LIMIT 1");
$image = pg_unescape_bytea(pg_fetch_result($rs, 0, 0));
?>

/Tobias