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sqlite_udf_decode_binary

(PHP 5 < 5.4.0, PECL sqlite >= 1.0.0)

sqlite_udf_decode_binary — Decode binary data passed as parameters to an UDF

说明

sqlite_udf_decode_binary ( string $data ) : string

Decodes binary data passed as parameters to a UDF.

You must call this function on parameters passed to your UDF if you need them to handle binary data, as the binary encoding employed by PHP will obscure the content and of the parameter in its natural, non-coded form.

PHP does not perform this encode/decode operation automatically as it would severely impact performance if it did.

参数

data: The encoded data that will be decoded, data that was applied by either sqlite_udf_encode_binary() or sqlite_escape_string().

返回值

The decoded string.

范例

Example #1 binary-safe max_length aggregation function example


<?php
$data = array(
   'one',
   'two',
   'three',
   'four',
   'five',
   'six',
   'seven',
   'eight',
   'nine',
   'ten',
   );
$db = sqlite_open(':memory:');
sqlite_query($db, "CREATE TABLE strings(a)");
foreach ($data as $str) {
    $str = sqlite_escape_string($str);
    sqlite_query($db, "INSERT INTO strings VALUES ('$str')");
}

function max_len_step(&$context, $string) 
{
    $string = sqlite_udf_decode_binary($string);
    if (strlen($string) > $context) {
        $context = strlen($string);
    }
}

function max_len_finalize(&$context) 
{
    return $context;
}

sqlite_create_aggregate($db, 'max_len', 'max_len_step', 'max_len_finalize');

var_dump(sqlite_array_query($db, 'SELECT max_len(a) from strings'));

?>

参见

sqlite_udf_encode_binary() - Encode binary data before returning it from an UDF
sqlite_create_function() - Registers a "regular" User Defined Function for use in SQL statements
sqlite_create_aggregate() - Register an aggregating UDF for use in SQL statements

User Contributed Notes

BenWa 26-Jun-2018 01:03


I had to migrate an existing SQLITE2 db with UDF encoded fields. SQLITE3 does not support sqlite_udf_decode_binary. So I wrote a replacement for the migration.



    function sqlite_udf_decode_binary($in){

      if ( substr($in,0,1)==chr(1) ) {

        $n=strlen($in);

        $e=ord(substr($in,1,1));

        $i=2 ;

        while($i<$n){

            $x = ord(substr($in,$i,1)) ;

            if ($x==1) {

                $i++;

                $x = ord(substr($in,$i,1)) - 1 ;

            } 

            $out .= chr($x+$e) ;

            $i++;

        }

          

      } else {

          $out = $in ;

      }

      return $out ;

    }

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sqlite_udf_decode_binary

说明

参数

返回值

范例

参见

User Contributed Notes

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