I have a code below:
<?php
require "institution.php"
/* in this portion, query for database connection is executed, and */
$institution= $_POST['institutionname'];
$sCampID = 'SELECT ins_id FROM institution where ins_name= '$institution' ';
$qcampID = pg_query($sCampID) or die("Error in query: $query." . pg_last_error($connection));
/* this portion outputs the ins_id */
?>
My database before has no mixed-case table names, that's why when I run this query, it shows no error at all. But because I've changed my database for some reasons, and it contains now mixed-case table names, i have to change the code above into this one:
$sCampID = 'SELECT ins_id FROM "Institution" where ins_name= '$institution' ';
where the Institution has to be double quoted. The query returned parse error.
When i removed this portion: where ins_name= '$institution', no error occured.
My question is how do I solve this problem where the table name which contains a mixed-case letter and a value stored in a variable ($institution in this case) will be combined in a single select statement?
Your answers and suggestions will be very much appreciated.
You can use the double quote instead
$sCampID = "SELECT ins_id FROM \"Institution\" where ins_name= '$institution'";
<?php
require "institution.php"
/* in this portion, query for database connection is executed, and */
$institution= pg_escape_string($_POST['institutionname']);
$sQuery = "SELECT ins_id FROM \"Institution\" where ins_name= '$institution'";
$qcampID = pg_query($sQuery)
or trigger_error("Error in query: $sQuery." . pg_last_error($connection));
/* this portion outputs the ins_id */
?>
Note
pg_escape_string as it ought to be used, not to protect from any injections but as just a part of the syntax.
trigger_error which should be used instead of echo (and note proper variable name)
and double quotes or your variable won't be extrapolated ( http://php.net/types.string for ref)
and slashes at double quotes (same ref)
$sCampID = 'SELECT ins_id FROM "Institution" where ins_name= \''.$institution.'\'';
String escaping.
As another commenter posted, read about SQL injection. What I have is not injection safe, consider using something with prepared statements, preferably PDO.
To add to other answers (quote the table name, and use prepared statements to gain security and performance), read about PG and tables case sensitivity. If you have the option, you might consider to change your db schema, so that tables names (and columns and identifiers in general) are all lowercase. That would simplify a little your queries - (but require you to check all your actual quoted queries and unquote them).
What happens if $institution contains the following string: ' or 1 = 1; --
That's what we call an SQL injection attack, and it's a super-easy way for hackers to steal your data -- and get you into big trouble with your customers.
You need to escape that string using pg_escape_string() before putting it into an SQL query. I like to use sprintf() to build my queries:
$sql = sprintf("SELECT ins_id FROM \"Institution\" where ins_name= '%s'", pg_escape_string($conn, $institution));
In the above example, $conn is the connection identifier, created by calling pg_connect().
Related
In my table i have query:
$sql="SELECT * FROM `jom_x1_organizatori`
WHERE Organizator='".$sta_dalje."' Order by `Struka`,`Zanimanje`";
$sta_dalje=$_POST["state_id"] from another table and value is:
ЈУ Гимназија са техничким школама Дервента
"ПРИМУС" Градишка
In case 1 working.
How to make query?
Firts of all: Never build the query by concatenating the query string with user input! If you do, then escape the input with the library's dedicated function (mysqli_real_escape_string for example). Without escaping you will open a potential security hole (called SQL injection).
"ПРИМУС" Градишка is not working because after concatenating, the query will be invalid. Now imagine, what happens, if I post the following input: '; DROP TABLE jom_x1_organizatori; --
Your query will be:
SELECT * FROM `jom_x1_organizatori`
WHERE Organizator=''; DROP TABLE jom_x1_organizatori; --' Order by `Struka`,`Zanimanje`
Whenever you can use prepared statements to bind parameters (and let the library to do the hard work), but always escape and validate your input (using prepared statements, escaping is done by the library)!
$sta_dalje = (sting)$_POST["state_id"]; // Do filtering, validating, force type convertation, etc!!
// Prepare the statement (note the question mark at the end: it represents the parameter)
$stmt = $mysqlLink->mysqli_prepare(
"SELECT * FROM `jom_x1_organizatori` WHERE Organizator = ?"
);
// Bind a string parameter to the first position
$stmt->bind_param("s", $sta_dalje);
For more info about prepared statements:
mysqli prepared statements
PDO prepared statements
Please note that the old mysql extension is deprecated, do not use it if not necessary!
Just a side note
Do not use SELECT * FROM, always list the columns. It prevents to query unnecessary data and your code will be more resistant to database changes, plus debugging will be a bit simplier task.
Use escape string
$sta_dalje = mysqli_real_escape_string($con, $_POST["state_id"]);
And your where condition can be simply
Organizator='$sta_dalje'
This is bizarre, I'm changing some code from mysql to mysqli functions cause of php 5.5+, in these two basic examples, mysql_query had no ' single quote nor ` backtick and worked fine.
$sql = "SELECT * FROM `".$table."`"; // requires: ` ` or fails
$result = mysqli_query($con,$sql);
$sql = "SHOW TABLES LIKE '".$table."'"; // requires: ' ' or fails
$result = mysqli_query($con,$sql);
Can someone explain why?
EDIT: I guess the essence of my question is that: Both functions worked fine without any kind of quotes with mysql_query, and both failed mysqli_query without some kind of quotes. Meaning I will have to fiddle around with half my query's when changing from mysql_ to mysqli_
In your first select statement you are trying to select a table by it's name, hence it will accept the name either with ` or without them, but now with single or double quotes. These should work :
$sql = "SELECT * FROM `table_name`";
$sql = "SELECT * FROM table_name";
In the second case you need to pass in a string to be compared by the like statement hence you need to surround it either with single ' or double " quotes:
$sql = "SHOW TABLES LIKE 'string'";
$sql = "SHOW TABLES LIKE \"string\"";
Edit:
Check out this previous answer on SO as well:
Using backticks around field names
Edit 2:
Since we (me and in comments) suggested that backticks are somehow optional, keep in mind that as a best practise use them whenever you can since although it will allow you to pass most queries without them, some queries using MySql reserved words would break when containing mysql reserved words
I do understand that the prepared statements is the ultimate way to seek protection against the SQL injection. However, they provide coverage in a limited fashion; for example, in cases where I let the user to decide how the order by operation to be ( i.e, is it ASC or DESC? etc ), I get no coverage there with the prepared statements.
I understand that I can map the user input to a pre-defined white list for that. But, this is only possible when a whitelist can be created or guessed thoroughly beforehand.
For example, in the cases I mention above ( the ASC, or DESC ), this can easily be mapped and verified against a list of accepted values. But isn't there a situation where the portion of the SQL statement cannot be verified against a white list?
If such a situation exists, then what's the recommended approach?
If I were to escape the user_input using the underlying database's built-in escape utility (such as mysqL_real_escape_string for mysql) across the board, where would I fail?
I'm asking this question with the assumption that I always construct my sql statements with quoted values - even for integers...
Let's take a look at the following example and reflect upon it..
select {$fields} from {$table} where Age='{$age}' order by {$orderby_pref}
Assume all vars are user supplied.
If I were to mysql_real_escape_string all the variables in the above SQL ( as opposed to using prepared statements which covers me only half-way forcing me to come up whitelists for the other half that it cannot help), wouldn't it be equally safe (and easier to code)? If not, in which input scenario escape utility would fail?
$fields = mysql_escape($fields);
$table = mysql_escape($table);
$age = mysql_escape($age);
$orderby_pref = mysql_escape($orderby_pref);
select {$fields} from {$table} where Age='{$age}' order by {$orderby_pref}
You always need to use white-lists for stuff like table- or column names, whether you use prepared statements or the mysql escape functions.
The problem is that table names and column names are not quoted in single or double quotes, so if you use a function that specifically quotes these characters (and some more of course...), it will do nothing for your table name.
Consider the table name my_table; DELETE * FROM mysql; SELECT * FROM my_table. Nothing in this string will get escaped by mysql's escape functions but it is definitely a string you would want to check against a white-list.
Apart from that the mysql escape functions have a problem with character sets that can render them useless, so you are always better off with prepared statements.
You could use PDO and your life will get easier ... :
# Order
switch(strtoupper($Order)){
default:
case 'ASC':
$Order = 'ASC';
break;
case 'DESC':
$Order = 'DESC';
break;
}
# ID
$ID = 39;
$Username = 'David';
# Query
$Query = $this->DB->Main->prepare('SELECT * FROM Table WHERE ID = :ID AND Username = :Username ORDER BY HellBob '.$Order);
$Query->bindValue(':ID', $ID, PDO::PARAM_INT);
$Query->bindValue(':Username', $Username, PDO::PARAM_STR);
# All good ?
if(!$Query->execute()){
exit('Error');
}
// Results
$Row = $Query->fetch(PDO::FETCH_ASSOC);
You don't have to worry about quotes or SQL injections. You can use simple "white list" as you mention to get variable into your query.
What is wrong with this query?
$query3 = "INSERT INTO Users
('Token','Long','Lat')
VALUES
('".$token."','".$lon1."','".$lat."')";
You have several issues with this.
Column names should be backtick escaped, not quoted (also LONG is a datatype in MySQL hence it's reserved and must be backtick-escaped).
You have SQL injection problems if those arguments aren't escaped.
You should provide us with the result of mysql_error() if it's not working.
Try running this code:
$token = mysql_real_escape_string($token);
$lon1 = mysql_real_escape_string($lon1);
$lat = mysql_real_escape_string($lat);
$query3 = "INSERT INTO `Users` (`Token`, `Long`, `Lat`)
VALUES ('{$token}', '{$lon1}', '{$lat}')";
$result3 = mysql_query($query3) or die("Query Error: " . mysql_error());
If that still doesn't work, give us the error message that's produced.
Long is the mysql reserved word and reserved words needs to be enclosed in backticks
$query3 = "INSERT INTO Users
(`Token`,`Long`,`Lat`)
VALUES
('".$token."','".$lon1."','".$lat."')";
You're using single quotes around your field names. This isn't valid in any SQL variant I know of. Either get rid of them or quote the field names in the correct way for your SQL flavor.
Your code likely has an SQL injection vulnerability, unless you left out the code that escapes $token etc
You shouldn't be putting values into the SQL string like that. This isn't the 1990s - we have parametrized queries now.
The mysql_ functions make it a bit difficult to do queries properly. Switch to either mysqli or PDO.
I have a searchable database of the House and Senate and I just want to make a simple web page that can search this database. The only problem is, while I'm comfortable writing SQL select statements, how do I properly format them for use in PHP?
For example, here's my radio button to select Senators by state:
$sql = "";
if ($_POST['pkChamber'] == "Senate") {
if ($_POST['pkParty'] == "Y") {
$sql = SELECT * FROM senateinfo
WHERE state = (Variable = "stname")
ORDER BY last_name, first_name');
}
else
{
$sql = SELECT * FROM senateinfo
WHERE state = (Variable = "stname")
ORDER BY last_name, first_name
}
}
I am not sure what you're asking for, But I have a good example of reliable and safe way for building WHERE statement dynamically:
$w = array();
$where = '';
if (!empty($_GET['rooms'])) $w[]="rooms='".mysql_real_escape_string($_GET['rooms'])."'";
if (!empty($_GET['space'])) $w[]="space='".mysql_real_escape_string($_GET['space'])."'";
if (!empty($_GET['max_price'])) $w[]="price < '".mysql_real_escape_string($_GET['max_price'])."'";
if (count($w)) $where = "WHERE ".implode(' AND ',$w);
$query = "select * from table $where";
Hope this helps.
Your query seems fine. I think you just need to understand some of the finer points of string parsing in PHP.
When you use double quotations (") to enclose a string, PHP actually will try to parse it looking for variables and/or other php code to process first. Something like this:
$sql = "SELECT * FROM table WHERE state = '{$state}' AND user = {$user->id}";
PHP will substitute out $state for whatever is defined in that variable and the same for the id of whatever user is instantiated in that class. (Also, you don't have to wrap your simple variables in {}. It does help with readability but is only required for class methods/variables.)
If you use single quotes (') to enclose a string, PHP simply treats it like normal. For your above query, I would suggest enclosing it in single quotes like this:
$sql = 'SELECT * FROM senateinfo WHERE state = (Variable = "stname") ORDER BY last_name, first_name)';
If you want to use variables later on in this query, then you will need to escape the double quotations that are in there like this:
$sql = "SELECT * FROM senateinfo WHERE state = (Variable = \"stname\") ORDER BY last_name, first_name)";
This way, PHP doesn't error out thinking you were trying to concatenate strings incorrectly when all you were doing was pasting a query.
You need to focus on one issue at a time.
Try to avoid writing SQL in PHP until you've a clear handle on strings in PHP, and how to inject variables into those strings. So:
Read up on string quoting in PHP (double quotes vs. Single quotes, and yes, HEREDOC)
Read up on variables in strings in PHP (note that if it doesn't have a $ dollar sign, it's a CONSTANT, not a string variable. Start off right with $strings and $variables where they're supposed to be used, not CONSTANTs, which only fall back to turn into strings if nothing else is available.)
Read up on binding SQL in PHP. Anything else will lead you down the path of SQL injection. If there are only naked strings used in your PHP SQL, then you are setting yourself up for failure when you finally deploy your web scripts to the harsh and unforgiving Internet. It's full of sharks ready to take advantage of SQL injection prone scripts.
Here is an example of code I use daily to bind SQL, centered around a custom function that makes it easy:
query("select * where someTable where someTable_id = :bound_id", array(':bound_id'=>13));
I can get you a function for creating bound SQL simply like that later (when I'm actually at a computer instead of mobile) if you're interested.
I use HEREDOCs for writing out non-trivial queries:
$sql = <<<EOL
SELECT blah, blah, blah
FROM table
WHERE (somefield = {$escaped_value}) ...
ORDER BY ...
HAVING ...
EOL;
Heredocs function as if you'd done a regular double-quoted string, but with the bonus of not having escape internal quotes. Variable interpolation works as expected, and you can do indentation on the text as well, so your query looks nicely formatted
I always do mine like this to keep it looking nice.
$sql = "SELECT * FROM senateinfo " .
"WHERE state = (Variable = "stname") " .
"ORDER BY last_name, first_name')";