如何使用php在SQL查询中转义引号？

Question

I have a query

$sql ="SELECT CustomerID FROM tblCustomer 
WHERE EmailAddress = '".addslashes($_POST['username']) ."' AND Password = '".addslashes($_POST['password']) ."'";

//  while printing,   it will be

SELECT CustomerID FROM tblCustomer WHERE EmailAddress = 'test@ab\'c.com' AND Password = '123'

if we executing this in a mysql server it works, but not in a sql server

what is the solution for this? . Iam using sql server

Answer 1

addslashes() will escape single quotes with a leading backslash which is valid syntax in MySQL but not in MS SQL Server. The correct way to escape a single quote in MS SQL Server is with another single quote. Use mysql_real_escape_string() for MySQL ( mysql_escape_string() has been deprecated). Unfortunately, no analogous mssql_ function exists so you'll have to roll your own using str_replace() , preg_replace() or something similar. Better yet, use a database neutral abstraction layer such as PDO that supports parameterized queries.

Answer 2

For MySQL, you want to use mysql_real_escape_string . addslashes does almost the same thing and has fewer letters, but apparently it gets some stuff wrong -- don't use it.

For SQL Server, it's a bit more complicated, as (1) MySQL quotes stuff non-standardly, and (2) i don't see a function made to quote stuff for SQL Server. However, the following should work for you...

$escaped_str = str_replace("'", "''", $unsafe_str);

Answer 3

for mysql

USE mysql_real_escape_string

http://php.net/manual/en/function.mysql-real-escape-string.php

like :

// Query
$query = sprintf("SELECT * FROM tblCustomer WHERE user='%s' AND password='%s'",
            mysql_real_escape_string($user),
            mysql_real_escape_string($password));

for mssql

look on the answers here :

How to escape strings in SQL Server using PHP?

Answer 4

You shouldn't really be building the SQL statement dynamically as it's dangerous (and unnecessary). The correct thing to do is to use a paramerised query see http://msdn.microsoft.com/en-us/library/cc296201%28SQL.90%29.aspx

$sql ="SELECT CustomerID FROM tblCustomer WHERE EmailAddress = ? AND Password = ?";
$stmt = sqlsrv_query( $conn, $sql, array($_POST['username'], $_POST['password']));

This is much safer and means you don't have to worry about escaping characters. Another thing is beware of case sensitive / insensitve comparisons. For example if you wanted email address to be case insensitive but password case sensitive use something like:

$sql ="SELECT CustomerID FROM tblCustomer WHERE EmailAddress = ? COLLATE SQL_Latin1_General_CP1_CIAI AND Password = ? COLLATE SQL_Latin1_General_CP1_CSAS";