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 have the following query
$products = $this->mysqliengine->query("select * from temp_all_product where download_status = 0") or die($this->mysqliengine->error());
$temp_status_update = $this->mysqliengine->prepare("update temp_all_product set download_status = ? where id = ?") or die($this->mysqliengine->error);
$temp_status_update->bind_result($download_status, $id);
while($product = $products->fetch_assoc()) {
$id = $product['id'];
$download_status = 1;
$temp_status_update->execute();
}
In the above statement I can select the values from temp table but unable to update the status. What is the problem here
You need to use bind_param in your update statement instead of bind_result.
$temp_status_update->bind_param('dd', $download_status, $id);
The 'dd' just tells the system that each input is a number.
http://www.php.net/manual/en/mysqli-stmt.bind-param.php
#eggyal was merely suggesting that you could replace all your code with a single update statement. Your remark about LIMIT does not make much sense.
Suggestion: If you don't have much invested in mysqli then switch to PDO. It allows using named parameters which can make your code more robust and easier to maintain:
$sql = "UPDATE temp_all_product SET download_status = :status where id = :id";
$stmt = $pdo->prepare($sql);
$stmt->execute(array('status' => 1, 'id' => $product['id']));
Plus you can configure it to throw exceptions so you don't need all this error checking.
http://www.php.net/manual/en/book.pdo.php
http://net.tutsplus.com/tutorials/php/pdo-vs-mysqli-which-should-you-use/
I can update my columns dynamically, but I dont know how to update it with set values (stupid I know)
This is my sql code that updates the columns with set values:
if (isset($_POST['delete'])) {
$sql = 'UPDATE users SET user_deletion_date = NOW(), user_deleted_by = '.$_SESSION['id'].', deleted = Y
WHERE user_id = ?';
if ($stmt->prepare($sql)) {
// bind the query parameters
$stmt->bind_param('i', $_GET['user_id']);
// bind the result to variables
$stmt->bind_result($user_id, $user_deletion_date, $user_deleted_by, $deleted);
// execute the query, and fetch the result
$done = $stmt->execute();
$stmt->fetch();
}
}
if ($done) {
header('Location: update_users_confirm.php');
exit;
}
this doesn't update the table at all, I know that the issue is with my bind_param, could someone please help
Michael B's answer is mostly likely the solution. Change the $_GET to $_POST
I am using mysqli prepared statments and I am trying to write a prepared statement with an UPDATE, but I think I am off somewhere.
Here's my code:
$upload_folder = 'Some String';
$sql = 'UPDATE orders (upload_location)
SET (?)
WHERE order_id = 160';
$stmt = $conn->stmt_init();
if($stmt->prepare($sql)){
$stmt->bind_param('s', $upload_folder);
$location_inserted = $stmt->execute();
}
What am I doing wrong?
SET foo = ?
You haven't specified which column to update.
the correct sql-syntax for update is:
UPDATE table SET column = ?
you are using SET keqword instead of VALUES as it's supposed by query format.
My site is rather extensive, and I just recently made the switch to PHP5 (call me a late bloomer).
All of my MySQL query's before were built as such:
"SELECT * FROM tablename WHERE field1 = 'value' && field2 = 'value2'";
This made it very easy, simple and friendly.
I am now trying to make the switch to mysqli for obvious security reasons, and I am having a hard time figuring out how to implement the same SELECT * FROM queries when the bind_param requires specific arguments.
Is this statement a thing of the past?
If it is, how do I handle a query with tons of columns involved? Do I really need to type them all out every time?
I could be wrong, but for your question I get the feeling that bind_param() isn't really the problem here. You always need to define some conditions, be it directly in the query string itself, of using bind_param() to set the ? placeholders. That's not really an issue.
The problem I had using MySQLi SELECT * queries is the bind_result() part. That's where it gets interesting. I came across this post from Jeffrey Way: http://jeff-way.com/2009/05/27/tricky-prepared-statements/(This link is no longer active). The script basically loops through the results and returns them as an array — no need to know how many columns there are, and you can still use prepared statements.
In this case it would look something like this:
$stmt = $mysqli->prepare(
'SELECT * FROM tablename WHERE field1 = ? AND field2 = ?');
$stmt->bind_param('ss', $value, $value2);
$stmt->execute();
Then use the snippet from the site:
$meta = $stmt->result_metadata();
while ($field = $meta->fetch_field()) {
$parameters[] = &$row[$field->name];
}
call_user_func_array(array($stmt, 'bind_result'), $parameters);
while ($stmt->fetch()) {
foreach($row as $key => $val) {
$x[$key] = $val;
}
$results[] = $x;
}
And $results now contains all the info from SELECT *. So far I found this to be an ideal solution.
"SELECT * FROM tablename WHERE field1 = 'value' && field2 = 'value2'";
becomes
"SELECT * FROM tablename WHERE field1 = ? && field2 = ?";
which is passed to the $mysqli::prepare:
$stmt = $mysqli->prepare(
"SELECT * FROM tablename WHERE field1 = ? && field2 = ?");
$stmt->bind_param( "ss", $value, $value2);
// "ss' is a format string, each "s" means string
$stmt->execute();
$stmt->bind_result($col1, $col2);
// then fetch and close the statement
OP comments:
so if i have 5 parameters, i could potentially have "sssis" or something (depending on the types of inputs?)
Right, one type specifier per ? parameter in the prepared statement, all of them positional (first specifier applies to first ? which is replaced by first actual parameter (which is the second parameter to bind_param)).
While you are switching, switch to PDO instead of mysqli, It helps you write database agnositc code and have better features for prepared statements.
http://www.php.net/pdo
Bindparam for PDO:
http://se.php.net/manual/en/pdostatement.bindparam.php
$sth = $dbh->prepare("SELECT * FROM tablename WHERE field1 = :value1 && field2 = :value2");
$sth->bindParam(':value1', 'foo');
$sth->bindParam(':value2', 'bar');
$sth->execute();
or:
$sth = $dbh->prepare("SELECT * FROM tablename WHERE field1 = ? && field2 = ?");
$sth->bindParam(1, 'foo');
$sth->bindParam(2, 'bar');
$sth->execute();
or execute with the parameters as an array:
$sth = $dbh->prepare("SELECT * FROM tablename WHERE field1 = :value1 && field2 = :value2");
$sth->execute(array(':value1' => 'foo' , ':value2' => 'bar'));
It will be easier for you if you would like your application to be able to run on different databases in the future.
I also think you should invest some time in using some of the classes from Zend Framwework whilst working with PDO. Check out their Zend_Db and more specifically [Zend_Db_Factory][2]. You do not have to use all of the framework or convert your application to the MVC pattern, but using the framework and reading up on it is time well spent.
Is this statement a thing of the past?
Yes. Don't use SELECT *; it's a maintenance nightmare. There are tons of other threads on SO about why this construct is bad, and how avoiding it will help you write better queries.
See also:
What is the reason not to use select *?
Performance issue in using SELECT *?
Why is using '*' to build a view bad?
You can still use it (mysqli is just another way of communicating with the server, the SQL language itself is expanded, not changed). Prepared statements are safer, though - since you don't need to go through the trouble of properly escaping your values each time. You can leave them as they were, if you want to but the risk of sql piggybacking is reduced if you switch.
you can use get_result() on the statement.
http://php.net/manual/en/mysqli-stmt.get-result.php
I was looking for a nice and complete example of how to bind multiple query parameters dynamically to any SELECT, INSERT, UPDATE and DELETE query. Alec mentions in his answer a way of how to bind result, for me the get_result() after execute() function for SELECT queries works just fine, and am able to retrieve all the selected results into an array of associative arrays.
Anyway, I ended up creating a function where I am able to dynamically bind any amount of parameters to a parametrized query ( using call_user_func_array function) and obtain a result of the query execution. Below is the function with its documentation (please read before it before using - especially the $paremetersTypes - Type specification chars parameter is important to understand)
/**
* Prepares and executes a parametrized QUERY (SELECT, INSERT, UPDATE, DELETE)
*
* #param[in] $dbConnection mysqli database connection to be used for query execution
* #param[in] $dbQuery parametrized query to be bind parameters for and then execute
* #param[in] $isDMQ boolean value, should be set to TRUE for (DELETE, INSERT, UPDATE - Data manipulaiton queries), FALSE for SELECT queries
* #param[in] $paremetersTypes String representation for input parametrs' types as per http://php.net/manual/en/mysqli-stmt.bind-param.php
* #param[in] $errorOut A variable to be passed by reference where a string representation of an error will be present if a FAUILURE occurs
* #param[in] $arrayOfParemetersToBind Parameters to be bind to the parametrized query, parameters need to be specified in an array in the correct order
* #return array of feched records associative arrays for SELECT query on SUCCESS, TRUE for INSERT, UPDATE, DELETE queries on SUCCESS, on FAIL sets the error and returns NULL
*/
function ExecuteMySQLParametrizedQuery($dbConnection, $dbQuery, $isDMQ, $paremetersTypes, &$errorOut, $arrayOfParemetersToBind)
{
$stmt = $dbConnection->prepare($dbQuery);
$outValue = NULL;
if ($stmt === FALSE)
$errorOut = 'Failed to prepare statement for query: ' . $dbQuery;
else if ( call_user_func_array(array($stmt, "bind_param"), array_merge(array($paremetersTypes), $arrayOfParemetersToBind)) === FALSE)
$errorOut = 'Failed to bind required parameters to query: ' . $dbQuery . ' , parameters :' . json_encode($arrayOfParemetersToBind);
else if (!$stmt->execute())
$errorOut = "Failed to execute query [$dbQuery] , erorr:" . $stmt->error;
else
{
if ($isDMQ)
$outValue = TRUE;
else
{
$result = $stmt->get_result();
if ($result === FALSE)
$errorOut = 'Failed to obtain result from statement for query ' . $dbQuery;
else
$outValue = $result->fetch_all(MYSQLI_ASSOC);
}
}
$stmt->close();
return $outValue;
}
usage:
$param1 = "128989";
$param2 = "some passcode";
$insertQuery = "INSERT INTO Cards (Serial, UserPin) VALUES (?, ?)";
$rowsInserted = ExecuteMySQLParametrizedQuery($dbConnection, $insertQuery, TRUE, 'ss', $errorOut, array(&$param1, &$param2) ); // Make sure the parameters in an array are passed by reference
if ($rowsInserted === NULL)
echo 'error ' . $errorOut;
else
echo "successfully inserted row";
$selectQuery = "SELECT CardID FROM Cards WHERE Serial like ? AND UserPin like ?";
$arrayOfCardIDs = ExecuteMySQLParametrizedQuery($dbConnection, $selectQuery, FALSE, 'ss', $errorOut, array(&$param1, &$param2) ); // Make sure the parameters in an array are passed by reference
if ($arrayOfCardIDs === NULL)
echo 'error ' . $errorOut;
else
{
echo 'obtained result array of ' . count($arrayOfCardIDs) . 'selected rows';
if (count($arrayOfCardIDs) > 0)
echo 'obtained card id = ' . $arrayOfCardIDs[0]['CardID'];
}