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pg_escape_bytea 转义 bytea 类型的二进制数据


pg_escape_bytea ( string $data ) : string

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。


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()pg_escape_string()

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User Contributed Notes 7 notes

ynzhang from lakeheadu of ca
12 years ago
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:

= 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:
Hayley Watson
3 years ago
PostgreSQL 9.0 introduced a new hexadecimal-based representation for bytea data that is preferred over the escaping mechanism implemented by this function.

function pg_escape_byteahex($binary)
10 years ago
To prevent any problems with encoding you could use hexadecimal or base64 input to save and retrieve data to the database:

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

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, $binData);
//echo "<pre>$binData</pre>";
7 years ago
using  pg_escape_bytea without 'E' escape tag
// Die Binärdaten maskieren
$escaped = pg_escape_bytea($data);

// und in die Datenbank einfügen (falsch/wrong)
pg_query("INSERT INTO gallery (name, data) VALUES ('Pine trees', E'$escaped')");

// und in die Datenbank einfügen (richtig/right)
pg_query("INSERT INTO gallery (name, data) VALUES ('Pine trees', '$escaped')");
gglockner AT NOSPAMdwaffler DOT com
11 years ago
If you're getting errors about nonstandard use of \\ in a string literal, then you need to escape the encoded bytea as follows:

= pg_escape_bytea($data);
pg_query("INSERT INTO gallery (name, data) VALUES ('Pine trees', E'$escaped'::bytea)");
php at tobias dot olsson dot be
18 years ago
if you need to change back bytea from the db to normal data, this will do that:

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));

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