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pg_unescape_bytea 取消 bytea 类型中的字符串转义


pg_unescape_bytea ( string $data ) : string

pg_unescape_bytea() 将 bytea 数据类型中的字符串取消转义。返回未转义的字符串(二进制)。


当 SELECT bytea 类型,PostgreSQL 返回用 \ 前导的八进制字节值(例如 \032)。用户需要自行将其转换回二进制格式。

本函数需要 PostgreSQL 7.2 或更新版本。在 PostgreSQL 7.2.0 和 7.2.1 中,当激活了多字节支持时必须强制转换为 bytea 类型,例如 INSERT INTO test_table (image) VALUES ('$image_escaped'::bytea);。PostgreSQL 7.2.2 或更新版本不需要强制转换。例外是当客户端和后端的字符编码不匹配时,有可能出现多字节流错误。用户必须强制转换为 bytea 来避免此错误。

参见 pg_escape_bytea()pg_escape_string()

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User Contributed Notes 3 notes

liviu dot mirea at gmail dot com
9 years ago
PostgreSQL 9.0 introduced "hex" as the new default format for encoding binary data. Because "pg_unescape_bytea" only works with the old "escape" format, you need to do pg_query('SET bytea_output = "escape";'); before executing your select queries.

More details can be found here:

[Ed: Recent PostgreSQL versions support unescaping the "hex" format.]
muralito at montevideo dot com dot uy
9 years ago
The workaround is to configure a property in the postgres database for the user, to make postgres behave as the old default.

ALTER USER username SET bytea_output = 'escape';

(or using the pgadmin interface)
tiagopastorello at gmail dot com
12 years ago
= pg_connect("host=localhost dbname=name user=postgres password=123456") or die('Sorry =( : ' . pg_last_error());

$cod= $_GET['cod'];

$sql = "SELECT * FROM table WHERE cod_field = '$cod'";
$quer = pg_query($conexao, $sql);

$reg = pg_fetch_object($query);

pg_unescape_bytea($reg -> field_bytea);

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