Is it possible, to use a dynamic value inside a SELECT FROM sql command?
Database->prepare("SELECT bomb FROM ? WHERE id=?")
->execute($strTable,$strID);
result:
Fatal error: Uncaught exception Exception with message Query error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near...
No. The table name cannot be a parameter of the query. You'd need to construct your query string first, concatenating the table name in.
Assuming $strTable is from a safe source just use
Database->prepare("SELECT bomb FROM $strTable WHERE id=?")
->execute($strID);
Your missing te bindParam statements. I don't think you can do the table name other than doing a php variable like #Alex did. Here is code for a prepared statement:
<?php
$stmt = $dbh->prepare("SELECT bomb FROM $tablename WHERE id=:strID");
$stmt->bindParam(':strID', $id);
$stmt->execute();
?>
PHP Manaual refernce: http://php.net/manual/en/pdo.prepared-statements.php
usually those database abstraction layer relies on prepared statement to handle the place holder feature. The prepared statement feature of the RDBM compile the query, I don't think it's possible to prepare the query if the table is not specified.
You should use the escapement function of your library and include the table name in the query.
example:
$tablename = escapement_function($strTable);
Database->prepare("SELECT bomb FROM {$tablename} WHERE id=?")
->execute($strID);
Related
In the mysql CLI I have prepared a statement like this:
PREPARE registrarUser FROM 'INSERT INTO Users (Users_name,Email,pass) values (?,?,?)'
In my database the prepared statements have to be done this way,instead of using a php method like this::
$conn->prepare("INSERT INTO Users (Users_name,Email,pass) VALUES (?, ?, ?)");
So I can't use the prepared statement or bind arguments.
I have tried this query which mimics the required statements in mysql CLI
$query = sprintf('
SET #Users_name = "%s";
SET #Email= "%s";
SET #pass = "%s";
EXECUTE registrarUser USING #Users_name, #Email, #pass;',$Users_name,$Email,$pass);
But it returns the following syntax error:
Errormessage: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'SET #Email= "eds#gmail.com"; SET #pass = "Thinkshap2"; EXECUTE registrar' at line 2
Does anyone know if there is a way to do it?
Thank you very much in advance;
No, it's not possible. Prepared statements have the session scope. Whenever you open a new connection in PHP, you open a new MySQL session. You can use PREPARE and EXECUTE in PHP, but both operations have to be done using the same session.
In other words, statements created with PREPARE do not persist on the database server. They only exist for the lifetime of the current session.
The reason why you are getting a syntax error in PHP is because you have concatenated multiple SQL statements together. You can't do that by default in PHP due to security considerations. Execute each one separately. For example, this works:
$stmt = $mysqli->query("PREPARE registrarUser FROM 'SELECT ?'");
$stmt = $mysqli->query("EXECUTE registrarUser USING 32");
Warning. Using PREPARE and EXECUTE from PHP defeats the main purpose of prepared statements usage in PHP. The main advantage is that you can separate variables from SQL syntax. You can't do that with PREPARE and EXECUTE. This is why both PDO and mysqli have prepared statements. Use mysqli::prepare() and mysqli_stmt::execute()
It's not possible.
From the MySQL manual
The scope of a prepared statement is the session within which it is created...
A prepared statement created in one session is not available to other sessions.
I have this function in PHP. I am trying to insert (if it's necessary) and then get the app_id from the table.
private function addApp($bundle_identifier,$os_id) {
$driver = new mysqli_driver();
$driver->report_mode = MYSQLI_REPORT_ALL;
//Insert or update app details
if ($stmt = $this->db->prepare("INSERT IGNORE INTO app (app_identifier,os_id) VALUES (?,?); SELECT app_id FROM app WHERE app_identifier = ? AND os_id = ?")){
$stmt->bind_param("ssss", $bundle_identifier,$os_id,$bundle_identifier,$os_id);
$stmt->execute();
$stmt->bind_result($app_id);
if (!isset($app_id)) {
echo "is set";
$app_id=$stmt->insert_id;
}
}
if($this->db->commit()){
return $app_id;
}
return 0;
}
The issue here is that stmt is always false with the error:
Uncaught exception 'mysqli_sql_exception' with message 'You have an
error in your SQL syntax; check the manual that corresponds to your
MySQL server version for the right syntax to use near 'SELECT app_id
FROM app WHERE app_identifier = ? AND os_id = ?' at line 1'
The weird thing is that this query works fine in my SQL.
Is that a limitation of mysqli?
According to http://php.net/manual/en/mysqli.prepare.php :
The query must consist of a single SQL statement.
Which basically answers your question. You have to use two db calls for two queries. Or use something like http://php.net/manual/en/mysqli.multi-query.php
The below is kept for information only as it refers PDO, while the question is about mysqli. It's generally useful though.
I think the reason for this working in mysql, but not in mysqli is that the latter supports prepared statements natively, while the former uses emulation. As your expression contains two queries, all bound parameters are given by driver to the first query (out of which is uses two and discards the other two). The second query then gets no parameters and therefore question marks are syntax errors. With prepared statements emulation PHP actually substitutes question marks with the properly escaped values and so forms two valid queries.
You can enable emulation using $db->setAttribute(PDO::ATTR_EMULATE_PREPARES, true), however, this may slightly affect performance.
See also http://www.php.net/manual/en/pdo.setattribute.php
I am trying to get a database query page to work but cant seem to do so.
my Code so far (here I tried bindValue, but previously tried bindParam and got the same result):
var_dump($_POST);
$dbh = new PDO ("mysql:host=$myServer;dbname=$myDB", $myUser, $myPw);
$columName = $_POST["columName"];
$tblName = $_POST["tblName"];
$valueName = $_POST["valueName"];
$specificValue = $_POST["specificValue"];
$stmt = $dbh->prepare("SELECT :columName FROM :tblName Where :valueName = :specificValue");
$stmt->bindValue(":columName", $columName);
$stmt->bindValue(":valueName", $valueName);
$stmt->bindValue(":tblName", $tblName);
$stmt->bindValue(":specificValue", $specificValue);
$stmt->execute();
$result = $stmt->fetch();
if(empty($result)){echo "empty";}
print_r ($stmt);
print_r($result);
Printing result and $stmt brings following results:
empty
PDOStatement Object ( [queryString] => SELECT :columName FROM :tblName Where :valueName = :specificValue )
What did I do wrong? What could I try to get it to work?
I am new to the whole coding thing, so please ask if I forgot any code or other important information!
Thanks!
Placeholder parameters can only represent VALUES in the query. Tables, field names, sql key words, etc.. are all impossible to use placeholders on.
If you need to build a dynamic query and replace field/table names, then you'll have to use good old string construction methods, and be aware that you'll be opening yourself to SQL injection attacks again:
$sql = "SELECT * FROM $foo WHERE $bar = :baz";
$stmt = $dbh->prepare($sql);
$stmt->bindValue(':baz', $baz);
I'm afraid you need to rethink how parameterised queries work. It's not just a case of magically inserting data in a safe way. It's about distingushing between the structure of a query and the data.
So the database name, the column names, the table names and any SQL keywords are part of the structure of the query. Every time you run the query, they will be the same.
The data, however, can change between running the query.
So the structure needs to be in place when the query is prepared. However, you obviously can't just plonk the $columName variable etc into the query for SQL injection reasons. If you really need to have flexible queries like this (nb that you probably don't) you need to create a whitelist of allowed values, either in your code or retrieved from the database.
Your query is invalid (you're using parameters for object identifiers) but you are not getting any notification because you have neither configured PDO to throw exceptions nor are calling the error check functions manually.
Add the PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION option to PDO's constructor:
$dbh = new PDO ("mysql:host=$myServer;dbname=$myDB", $myUser, $myPw, array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION));
Once you do so, you'll get a prompt exception on the exact issue, e.g.:
PDOException: SQLSTATE[42000]: Syntax error or access violation: 1064
You have an error in your SQL syntax; check the manual that
corresponds to your MySQL server version for the right syntax to use
near ''user' Where 'login' = 'john'' at line 1 in [...]
As you can see, this is trying to run a query like (e.g.):
SELECT 'user_id'
FROM 'user'
Where 'login' = 'john'
Additionally, beware of SQL injection. It's terribly unsafe to compose SQL queries using data from $_POST.
I am coming across a problem when deleting data from my SQL data. I have tried various versions of my statement but to no avail. Below is the error I am presented with and the statement I am using.
$sql = "DELETE FROM `saved_holidays` WHERE (subscriberID= $user AND title= $check_value)";
//connect to database then execute the SQL statement.
$db->exec($sql);
and the error message is:
SQLSTATE[42000]: Syntax error or access violation: 1064 You have an
error in your SQL syntax; check the manual that corresponds to your
MySQL server version for the right syntax to use near '#xml119.com AND
title= Luxurious Jamaican holidays | 40% Discount On Accommodati' at
line 1
I can see that the correct data is being passed but the syntax is wrong. Can anyone help?
$check_value is a string, so you have to enclose it in ' in your query like this:
title = '$check_value'
For security purposes, you should also use mysql_real_escape_string on all string parameters you have. Or even better, use prepared statements: http://php.net/manual/en/pdo.prepared-statements.php
You need to put quotations around your variables. It doesn't like spaces.
Depending on the server you are using (MySQL or MSSQL) you have to use backticks, single quotes, or double quotes:
DELETE FROM saved_holidays WHERE (subscriberID="$user" AND title="$check_value")
Also, if you are using PDOs, you should consider using prepared statements:
$statment = $conn->prepare("DELETE FORM saved_holidays WHERE (subscriberID=? AND title=?)"); //$conn has to be your connection ceated by doing new PDO(...connection string...)
$statment->execute(array($user, $check_value));
Amit is correct your statement should look like this;
$sql = "DELETE FROM `saved_holidays` WHERE (subscriberID= '$user' AND title= '$check_value')";
the variable is a string so must be enclosed in single quotes.
This should then work for you.
I'm having a problem with a query prepared in PHP with PDO. The code:
$link = new PDO("mysql:dbname=$dbname;host=127.0.0.1",$username,$password);
$link->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$query = $link->prepare("SELECT locality_name FROM :passedday GROUP BY locality_name ORDER BY locality_name DESC");
$query->bindParam(":passedday",$day); //Where day is, well, a day passed to the script elsewhere
$query->execute();
$result = $query->fetchAll();
$link = null;
//Do things with the $result.
The error message I am getting is:
SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''05_26_09' GROUP BY locality_name ORDER BY locality_name DESC' at line 1
When I execute the query on the server directly, it returns the appropriate result set without any problem. Any ideas what I'm doing wrong?
TIA.
Edit:
$day is passed as a GET argument. So, http://127.0.0.1/day.php?day=05_26_09 leads to $day = $_GET['day'];.
If 05_26_09 is supposed to bet the table's name, then I guess you've an escaping problem. Is your local operating system different from the live server?
I don't think you can use bindValue()/bindParam() for something else than values (eg. table name, field name). So I'm a bit suprised, that it works on your local system.
PDO uses mysql's C-API for prepared statements.
http://dev.mysql.com/doc/refman/5.0/en/mysql-stmt-prepare.html says:The markers are legal only in certain places in SQL statements. [...] However, they are not allowed for identifiers (such as table or column names)As a rule of thumb I use: "if you can't wrap it in single-quotes in an ad-hoc query string you can't parametrize it in a prepared statement"