How to Safely Escape Strings for SQL Server Queries in PHP?

Escaping Strings in SQL Server Using PHP

In the realm of database programming, preventing SQL injection attacks is of paramount importance. Escaping strings destined for SQL queries is a crucial step in safeguarding against malicious exploits.

When dealing with SQL Server specifically, many developers wonder about the alternative to the deprecated mysql_real_escape_string() function from PHP. While addslashes() may seem like a straightforward replacement, it falls short in some situations.

The Hex Bytestring Solution

For a comprehensive solution, consider converting the data into a hex bytestring. This approach ensures universal compatibility with all data types:

$unpacked = unpack('H*hex', $data);
mssql_query('
    INSERT INTO sometable (somecolumn)
    VALUES (0x' . $unpacked['hex'] . ')
');

Abstracted Function for Escaping

To simplify the process, you can define a custom function:

function mssql_escape($data) {
    if(is_numeric($data))
        return $data;
    $unpacked = unpack('H*hex', $data);
    return '0x' . $unpacked['hex'];
}

mssql_query('
    INSERT INTO sometable (somecolumn)
    VALUES (' . mssql_escape($somevalue) . ')
');

Alternative to mysql_error()

For handling errors in SQL Server, use the mssql_get_last_message() function, which provides similar functionality to mysql_error().

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