I am very worried about sql injection. I have been reading up about it and been trying to prepare the following query:
$query_AcousticDB = "SELECT * FROM products WHERE Category = 'Acoustic ' ORDER BY RAND()";
$AcousticDB = mysqli_query($DB, $query_AcousticDB) or die(mysqli_connect_error());
$row_AcousticDB = mysqli_fetch_assoc($AcousticDB);
$totalRows_AcousticDB = mysqli_num_rows($AcousticDB);
which works great.
I thought that I only have to change to the following:
$query_AcousticDB = prepare("SELECT * FROM products WHERE Category = 'Acoustic ' ORDER BY RAND()");
However this doesn't work. I get the following error:Call to undefined function prepare()
I still would like to get my values as:<?php echo $row_AcousticDB['what ever']; ?>
Can somebody point me into the right direction?
How about this?
$category = "Acoustic";
$sql = "SELECT * FROM products WHERE Category = ? ORDER BY RAND()";
$stmt = $DB->prepare($sql);
$stmt->bind_param('s', $category);
$stmt->execute();
$row_AcousticDB = $stmt->get_result(); // altenative: $stmt->bind_result($row_AcousticDB);
$row_AcousticDB->fetch_array(MYSQLI_ASSOC)
If you let the user enter any data (in text boxes on website) or you pull anything out of database for use (risk of second order injection) make sure you sanitize it (cleanse it of any nasty tags like < or >) by using htmlspecialchars($category) or htmlentities($category).
With this method implemented into your code, you will be reasonably safe from SQL Injection :)
Try to make this variable global: Put this on the upper part of your script global $acousticDB; or else you may try this $acoustic='';
Related
How can I add ORDER BY field to the end of this SQL query
$sql = "SELECT item_id,field FROM item WHERE department=".$catid;? I can't get the syntax right due to the PHP variable at the end...
I tried $sql = "SELECT item_id,field FROM item WHERE department=".$catid ORDER BY field; but obviously that didn't work
You can fix your syntax error like this, using another concatenation operator . to append the ORDER BY clause:
$sql = "SELECT item_id,field FROM item WHERE department=".$catid." ORDER BY field";
As long as $catid is an integer, that will work, but it may leave you open to SQL injection, dependent on the source of the value in $catid.
Best practice is to use a prepared query. For MySQLi, something like this:
$sql = "SELECT item_id,field FROM item WHERE department=? ORDER BY field";
$stmt = $conn->prepare($sql);
$stmt->bind_param('i', $catid); // change to 's' if $catid is a string
$stmt->execute();
$result = $stmt->get_result();
while ($row = $result->fetch_assoc()) {
// do something with results
}
I'm having some trouble using a variable declared in PHP with an SQL query. I have used the resources at How to include a PHP variable inside a MySQL insert statement but have had no luck with them. I realize this is prone to SQL injection and if someone wants to show me how to protect against that, I will gladly implement that. (I think by using mysql_real_escape_string but that may be deprecated?)
<?php
$q = 'Hospital_Name';
$query = "SELECT * FROM database.table WHERE field_name = 'hospital_name' AND value = '$q'";
$query_result = mysqli_query($conn, $query);
while ($row = mysqli_fetch_assoc($query_result)) {
echo $row['value'];
}
?>
I have tried switching '$q' with $q and that doesn't work. If I substitute the hospital name directly into the query, the SQL query and PHP output code works so I know that's not the problem unless for some reason it uses different logic with a variable when connecting to the database and executing the query.
Thank you in advance.
Edit: I'll go ahead and post more of my actual code instead of just the problem areas since unfortunately none of the answers provided have worked. I am trying to print out a "Case ID" that is the primary key tied to a patient. I am using a REDCap clinical database and their table structure is a little different than normal relational databases. My code is as follows:
<?php
$q = 'Hospital_Name';
$query = "SELECT * FROM database.table WHERE field_name = 'case_id' AND record in (SELECT distinct record FROM database.table WHERE field_name = 'hospital_name' AND value = '$q')";
$query_result = mysqli_query($conn, $query);
while ($row = mysqli_fetch_assoc($query_result)) {
echo $row['value'];
}
?>
I have tried substituting $q with '$q' and '".$q."' and none of those print out the case_id that I need. I also tried using the mysqli_stmt_* functions but they printed nothing but blank as well. Our server uses PHP version 5.3.3 if that is helpful.
Thanks again.
Do it like so
<?php
$q = 'mercy_west';
$query = "SELECT col1,col2,col3,col4 FROM database.table WHERE field_name = 'hospital_name' AND value = ?";
if($stmt = $db->query($query)){
$stmt->bind_param("s",$q); // s is for string, i for integer, number of these must match your ? marks in query. Then variable you're binding is the $q, Must match number of ? as well
$stmt->execute();
$stmt->bind_result($col1,$col2,$col3,$col4); // Can initialize these above with $col1 = "", but these bind what you're selecting. If you select 5 times, must have 5 variables, and they go in in order. select id,name, bind_result($id,name)
$stmt->store_result();
while($stmt->fetch()){ // fetch the results
echo $col1;
}
$stmt->close();
}
?>
Yes mysql_real_escape_string() is deprecated.
One solution, as hinted by answers like this one in that post you included a link to, is to use prepared statements. MySQLi and PDO both support binding parameters with prepared statements.
To continue using the mysqli_* functions, use:
mysqli_prepare() to get a prepared statement
mysqli_stmt_bind_param() to bind the parameter (e.g. for the WHERE condition value='$q')
mysqli_stmt_execute() to execute the statement
mysqli_stmt_bind_result() to send the output to a variable.
<?php
$q = 'Hospital_Name';
$query = "SELECT value FROM database.table WHERE field_name = 'hospital_name' AND value = ?";
$statement = mysqli_prepare($conn, $query);
//Bind parameter for $q; substituted for first ? in $query
//first parameter: 's' -> string
mysqli_stmt_bind_param($statement, 's', $q);
//execute the statement
mysqli_stmt_execute($statement);
//bind an output variable
mysqli_stmt_bind_result($stmt, $value);
while ( mysqli_stmt_fetch($stmt)) {
echo $value; //print the value from each returned row
}
If you consider using PDO, look at bindparam(). You will need to determine the parameters for the PDO constructor but then can use it to get prepared statements with the prepare() method.
I am new to PHP and have a really basic question.
If I know the result of a query is only a single value (cell) from a single row in MySQL how can I simplify the below without having to go through an array of results and without increasing the risk of SQL injection ?
In the example below I would just need to echo a single email as the result of the query.
I found a couple of posts suggesting different approaches with fetch_field for this but I am not sure what is the best way here since some of these seem to be pretty old or deprecated now.
My PHP:
$stmt = $conn->prepare("SELECT email FROM Users WHERE userName = ? LIMIT 1");
$stmt->bind_param('s', $userName);
$stmt->execute();
$result = $stmt->get_result();
$arr = $result->fetch_assoc();
echo $arr["email"];
Many thanks in advance.
You can avoid caring what the column is called by just doing this:
<?php
$stmt = $conn->prepare("SELECT email FROM Users WHERE userName = ? LIMIT 1");
$stmt->bind_param('s', $userName);
$stmt->execute();
$email = $stmt->get_result()->fetch_object()->email;
echo $email;
I'm sorry if this is a duplicate question but I don't know how to solve my problem. Every time I try to correct my error I fail. My code is:
if (isset($_GET["comment"])) {$id = $_GET["comment"];}
$query = "SELECT * FROM posts WHERE id = {$id['$id']};";
$get_comment = mysqli_query($con, $query);
Can anybody correct the code to not show an error anymore and tell me what did I wrong?
Try this:
$id = isset($_GET['comment']) ? $_GET['comment'] : 0;
$query = "SELECT * FROM `posts` WHERE `id` = " . intval($id);
The use of intval will protect you from SQL injection in this particular case. Ideally, you should learn PDO as it is extremely powerful and makes prepared statements much easier to handle to prevent all injections.
An example using PDO might look like:
$id = isset($_GET['comment']) ? $_GET['comment'] : 0;
$query = $pdo->prepare("SELECT * FROM `posts` WHERE `id` = :id");
$query->execute(array("id"=>$id));
$result = $query->fetch(PDO::FETCH_ASSOC); // for a single row
// $results = $query->fetchAll(PDO::FETCH_ASSOC); // for multiple rows
var_dump($result);
First of all you should prevent injestion.
if (isset($_GET["comment"])){
$id = (int)$_GET["comment"];
}
Notice, $id contanis int.
$query = "SELECT * FROM posts WHERE id = {$id}";
Assuming your $id is an integer and you only want to make the query if it is set, here's how you could do it using prepared statements, which protect you from MYSQL injection attacks:
if (isset($_GET["comment"])) {
$id = $_GET["comment"];
$stmt = mysqli_prepare($con, "SELECT * FROM posts WHERE id = ?");
mysqli_stmt_bind_param($stmt, 'i', $id);
mysqli_stmt_execute($stmt);
mysqli_stmt_bind_result($stmt, $get_comment);
while (mysqli_stmt_fetch($stmt)) {
// use $get_comment
}
mysqli_stmt_close($stmt);
}
Most of these functions return a boolean indicating whether they were successful or not, so you might want to check their return values.
This approach looks a lot more heavy duty and is arguably overkill for a simple case of a statement containing a single integer but it's a good practice to get into.
You might want to look at the object-oriented style of mysqli which you might find a little cleaner-looking, or alternatively consider using PDO.
I'm just migrating my code from mysql_query style commands to PDO style and I ran into a problem. THe old code looked like this :
$query_list_menu = "SELECT ".$_GET['section_name']." from myl_menu_hide_show WHERE id='".$_GET['id']."'";
And the updated code looks like below. Apparently it's not working. I store in $_GET['section_name'] a string that represents a field name from the database. But I think there is a problem when I pass it as a variable. Is the below code valid ? Thanks.
$query_list_menu = "SELECT :section_name from myl_menu_hide_show WHERE id=:id";
$result_list_menu = $db->prepare($query_list_menu);
$result_list_menu->bindValue(':section_name', $_GET['section_name'] , PDO::PARAM_STR);
$result_list_menu->bindValue(':id', $_GET['id'] , PDO::PARAM_INT);
$result_list_menu->execute();
If $_GET['section_name'] contains a column name, your query should be:
$query_list_menu = "SELECT " . $_GET['section_name'] . " from myl_menu_hide_show WHERE id=:id";
Giving:
$query_list_menu = "SELECT :section_name from myl_menu_hide_show WHERE id=:id";
$result_list_menu = $db->prepare($query_list_menu);
$result_list_menu->bindValue(':id', $_GET['id'] , PDO::PARAM_INT);
$result_list_menu->execute();
The reason is that you want the actual name of the column to be in the query - you'd changed it to be a parameter, which doesn't really make much sense.
I'll also add that using $_GET['section_name'] directly like this is a massive security risk as it allows for SQL injection. I suggest that you validate the value of $_GET['section_name'] by checking it against a list of columns before building and executing the query.
There is no good and safe way to select just one field from the record based on the user's choice. The most sensible solution would be to select the whole row and then return the only field requested
$sql = "SELECT * from myl_menu_hide_show WHERE id=?";
$stmt = $db->prepare($query_list_menu);
$stmt->execute([$_GET['id']]);
$row = $stmt->fetch();
return $row[$_GET['section_name']] ?? false;