I am building a SQL query that dynamically changes based on passed in $_GET parameters. I simply want to know if putting in a 'dummy' constraint is an 'acceptable' practice, so I do not have to check the SQL string for the existence of 'where' before I add new constraints (each time).
For example, the 'dummy' constraint':
$sql = "select * from users u where u.id != 0";
Now, in each block where I determine if I have to add more constraints, I can just do:
if (!empty($uid))
$sql .= " and (u.id = {$uid})";
Instead of doing:
if (!empty($uid)) {
$sql .= strpos($sql, "where") === false ? " where " : " and ";
$sql .= " (u.id = {$uid})";
}
I've used that convention (although I usually use WHERE 1=1 AND.) Depending on your RDBMS, using a column there could affect performance. For example, if you had an index that would otherwise be a covering index except for that column.
Please make sure that you understand the potential pitfalls of this kind of dynamic SQL, but if it's what you ultimately end up doing, adding that extra bit seems to make sense to me.
Instead of appending to the SQL string for each check, you could collect the conditions:
if ($_GET["uid"]) {
$where[] = array("u.id =", $_GET->sql["uid"]);
if ($_GET["photo"]) {
$where[] = array("u.has_photo =", 1);
And complete the SQL string when you're through:
foreach ($where as $add) {
$sql .= ...;
}
Otherwise, it's an acceptable approach. I wouldn't turn out the big weapons and use a full blown ORM query builder for that.
from the manual
SELECT * FROM table WHERE 1
so yes, you can do that
Related
I have a sql query that is generated using php. It returns the surrogate key of any record that has fields matching the search term as well as any record that has related records in other tables matching the search term.
I join the tables into one then use a separate function to retrieve a list of the columns contained in the tables (I want to allow additions to tables without re-writing php code to lower ongoing maintenance).
Then use this code
foreach ($col_array as $cur_col) {
foreach ($search_terms_array as $term_searching) {
$qry_string.="UPPER(";
$qry_string.=$cur_col;
$qry_string.=") like '%";
$qry_string.=strtoupper($term_searching);
$qry_string.="%' or ";
}
}
To generate the rest of the query string
select tbl_sub_model.sub_model_sk from tbl_sub_model inner join [about 10 other tables]
where [much code removed] or UPPER(tbl_model.image_id) like '%HONDA%' or
UPPER(tbl_model.image_id) like '%ACCORD%' or UPPER(tbl_badge.sub_model_sk) like '%HONDA%'
or UPPER(tbl_badge.sub_model_sk) like '%ACCORD%' or UPPER(tbl_badge.badge) like '%HONDA%'
or UPPER(tbl_badge.badge) like '%ACCORD%' group by tbl_sub_model.sub_model_sk
It does what I want it to do however it is vulnerable to sql injection. I have been replacing my mysql_* code with pdo to prevent that but how I'm going to secure this one is beyond me.
So my question is, how do I search all these tables in a secure fashion?
Here is a solution that asks the database to uppercase the search terms and also to adorn them with '%' wildcards:
$parameters = array();
$conditions = array();
foreach ($col_array as $cur_col) {
foreach ($search_terms_array as $term_searching) {
$conditions[] = "UPPER( $cur_col ) LIKE CONCAT('%', UPPER(?), '%')";
$parameters[] = $term_searching;
}
}
$STH = $DBH->prepare('SELECT fields FROM tbl WHERE ' . implode(' OR ', $conditions));
$STH->execute($parameters);
Notes:
We let MySQL call UPPER() on the user's search term, rather than having PHP call strtoupper()
That should limit possible hilarious/confounding mismatched character set issues. All your normalization happens in one place, and as close as possible to the moment of use.
CONCAT() is MySQL-specific
However, as you tagged the question [mysql], that's probably not an issue.
This query, like your original query, will defy indexing.
Try something like this using an array to hold parameters. Notice % is added before and after term as LIKE %?% does not work in query string.PHP Manual
//Create array to hold $term_searching
$data = array();
foreach ($col_array as $cur_col) {
foreach ($search_terms_array as $term_searching) {
$item = "%".strtoupper($term_searching)."%";//LIKE %?% does not work
array_push($data,$item)
$qry_string.="UPPER(";
$qry_string.=$cur_col;
$qry_string.=") LIKE ? OR";
}
}
$qry_string = substr($qry_string, 0, -3);//Added to remove last OR
$STH = $DBH->prepare("SELECT fields FROM table WHERE ". $qry_string);//prepare added
$STH->execute($data);
EDIT
$qry_string = substr($qry_string, 0, -3) added to remove last occurrence of OR and prepare added to $STH = $DBH->prepare("SElECT fields FROM table WHERE". $qry_string)
I'm having a little trouble with my MYSQL query
I have a DB full of products and I have a dropdown menu which lets a user select what time of day they'd like to get get results for :-
Dropdown
Breakfast
Lunch
Evening
Anytime
At the moment my statement is
SELECT * from DEALS WHERE timeofday='post data from form';
Now this works fine, but with the option for 'Anytime' I'd like the query to be able to search for results of all/any of the above.
I was thinking of perhaps doing an IF statement which fires off 2 separate queries, one which says if the $_POST['timeofday'] == 'Anytime' then fire off
SELECT * from DEALS where timeofday='Breakfast'
OR timeofday='Lunch' OR timeofday='Evening';
otherwise just do the normal query, although wondered if it was possible to do this in just one statement.
Kind regards
$query = 'SELECT * from DEALS';
if ($_POST['timeofday'] != 'Anytime') {
$query .= ' WHERE timeofday="' . $_POST['timeofday'] . '"';
}
As DCoder mentioned, this approach is vulnerable to sql injection... You should check/sanitize the input or use prepared statements. In this case where there is a predefined set of values you can:
$knownTimesOfDay = array('Breakfast', 'Lunch', 'Evening', 'Anytime');
if (!in_array($_POST['timeofday'])) {
die('Unsuppotred time of day... Did it really come from the form?');
}
$query = 'SELECT * from DEALS';
if ($_POST['timeofday'] != 'Anytime') {
$query .= ' WHERE timeofday="' . $_POST['timeofday'] . '"';
}
Don't think it can be done in one statement.
You are going to have to use an if statement anyhow.
if these are the only 3 possible values for timeofday,then you can have an if in the php script like this:
if($_POST['timeofday'] != 'Anytime' )
sql .= "where timeofday='".$_POST['timeofday']."'";
This could turn out to be negative depending on the items you have in the table, but you could use:
SELECT * from DEALS where timeofday LIKE '%{$post_data}%'
It would return all the results from timeofday if $post_data was an empty string.
I need some guidance to make an advanced search script for a website I'm working on.
I already know how to search the database for simple queries. The problem I'm encountering right now is how to search, when using multiple select boxes. For example:
This is just a simple form with different search options. The question is:
The visitor can choose to search on a country or city, both or even with all three options.
How do I catch that in the PHP script? Do I have to check if for example a city has been chosen, and fire a query based on that? But if I do that I would have to make different queries based on each select option.
In pseudo-code it would be something like this: (I imagine)
if country and city and something else is not null, launch a query to search in all three tables in the database.
But what to do when just the country has been chosen? Or just the city?
Is there a simple way to accomplish this?
Thanks in advance.
I like using an array to join conditions so I don't have to worry about leading or trailing AND's.
$conditions = array();
if ($formCondition1) {
$conditions[] = 'state = "'.$somevalue.'"';
}
if ($formCondition2) {
$conditions[] = 'country = "'.$somevalue.'"';
}
...
if ($formConditionN) {
$conditions[] = 'N = "'.$somevalue.'"';
}
//finally join the conditions together, the simplest case is with ANDs (if you need to add ORs, which it sounds like you don't, then this code would be a bit more complex)
$sqlStatement = 'SELECT field1, field2 FROM tableABC WHERE '.implode(' AND ', $conditions);
EDIT: don't forget to escape the input to prevent injection attacks, and of course test to make sure there are at least 1 condition before running the query.
EDIT: lol jswolf and I think very much alike :)
I make a $where array, add my conditions to it as necessary, and then implode it with ' AND ' as the glue. So something like:
$where = array();
if $city is defined
$where[] = "city = '".mysql_real_escape_string($city)."'";
fi
if $country is defined
$where[] = "country = '".mysql_real_escape_string($country)."'";
fi
...
if(count($where)) {
$query.= ' WHERE '.implode(' AND ', $where);
}
I would try something like:
$qry = "SELECT * FROM table WHERE ";
if ($country != '') {
$qry .= "country='".mysql_real_escape_string($country)."' AND "
}
if ($city != '') {
$qry .= "city='".mysql_real_escape_string($city)."' AND "
}
$qry .= '1';
$res = mysql_query($qry);
The query is built up depending on what is set. Note the "1" on the end of the query string which is always true. This is needed to follow the "WHERE" if $country and $city are both empty, or to follow the last "AND" if they are not.
I'd like to create a query in MySQL that has an optional value. When the value is specified the query is filtered by that value, when the value is not all rows are returned. Here's the idea:
public function doQuery($item = 'ANY_VALUE') {
$query = "SELECT * FROM table WHERE item = ?";
db->fetchAll($query,array($item))
...
}
doQuery(); // Returns everything
doQuery($item='item1'); // Returns only rows where item = 'item1'
Is there an easy way to do this without creating two query strings depending on the value of $item?
As far as I know, no such "any" placeholder exists.
If you can use LIKE, you could do
SELECT * FROM table WHERE item LIKE '%'
if you can append a condition, you could nullify the item clause like this:
SELECT * FROM table WHERE item = ? OR 1=1
(won't work in your example though, because you are passing "item" as a parameter)
That's all the options I can see - it's probably easiest to work with two queries, removing the WHERE clause altogether in the second one.
This would probably work, but I*m not sure whether it's a good idea from a database point of view.
public function doQuery($item = 'ANY_VALUE') {
$query = "SELECT * FROM table WHERE item = ? OR 1 = ?";
db->fetchAll($query,array($item, ($item == 'ANY_VALUE' ? 1 : 0))
...
}
Better way to do this is first generate sql query from the parameter you need to bother on, and then execute.
function doQuery($params) {
$query = 'SELECT * FROM mytable ';
if (is_array($params) // or whatever your condition ) {
$query .= 'WHERE item = ' . $params[0];
}
$query .= ' ;';
// execute generated query
execute($query);
}
You cannot get distinct results without giving distinct query strings.
Using $q = "... WHERE item = '$item'" you DO create distinct query strings depending on the value of $item, so it is not that different from using
$q = "..." . ($item=='ANY_VALUE' ? something : s_th_else);.
That said I see two or three options:
use function doQuery($item = "%") { $query = "SELECT ... WHERE item LIKE '$item'"; ...}
But then callers to that function must know that they must escape a '%' or '_' character properly if they want to search for an item having this character literally (e.g. for item = "5% alcoholic solution", giving this as argument would also find "50-50 sunflower and olive oil non alcoholic solution".
use function doQuery($item = NULL) { $query = "SELECT ..."; if ($item !== NULL) $query .= " WHERE item = '$item' "; ...} (where I use NULL to allow any other string or numerical value as a valid "non-empty" argument; in case you also want to allow to search for NULL (without quotes) you must choose another "impossible" default value, e.g., [], and you must anyway use a distinct query without the single quotes which however are very important in the general case), or even:
use function doQuery($item = NULL) { if($item === NULL) $query = "SELECT ..."; else $query = "SELECT ... WHERE item = '$item' "; ...}, which is more to type but probably faster since it will avoid an additional string manipulation (concatenation of the first and second part).
I think the 2nd & 3rd options are better than the first one. You should explain why you want to avoid these better solutions.
PS: always take care of not forgetting the quotes in the SQL, and even to properly escape any special characters (quotes, ...) in arguments which can depend on user input, as to avoid SQL injections. You may be keen on finding shortest possible solutions (as I am), but neglecting such aspects is a no-no: it's not a valid solution, so it's not the shortest solution!
how do you embed your sql scripts in php? Do you just write them in a string or a heredoc or do you outsource them to a sql file? Are there any best practices when to outsource them ? Is there an elegant way to organize this?
Use a framework with an ORM (Object-Relational Mapping) layer. That way you don't have to put straight SQL anywhere. Embedded SQL sucks for readability, maintenance and everything.
Always remember to escape input. Don't do it manually, use prepared statements. Here is an example method from my reporting class.
public function getTasksReport($rmId, $stage, $mmcName) {
$rmCondition = $rmId ? 'mud.manager_id = :rmId' : 'TRUE';
$stageCondition = $stage ? 't.stage_id = :stageId' : 'TRUE';
$mmcCondition = $mmcName ? 'mmcs.username = :mmcName' : 'TRUE';
$sql = "
SELECT
mmcs.id AS mmc_id,
mmcs.username AS mmcname,
mud.band_name AS mmc_name,
t.id AS task_id,
t.name AS task,
t.stage_id AS stage,
t.role_id,
tl.id AS task_log_id,
mr.role,
u.id AS user_id,
u.username AS username,
COALESCE(cud.full_name, bud.band_name) AS user_name,
DATE_FORMAT(tl.completed_on, '%d-%m-%Y %T') AS completed_on,
tl.url AS url,
mud.manager_id AS rm_id
FROM users AS mmcs
INNER JOIN banduserdetails AS mud ON mud.user_id = mmcs.id
LEFT JOIN tasks AS t ON 1
LEFT JOIN task_log AS tl ON tl.task_id = t.id AND tl.mmc_id = mmcs.id
LEFT JOIN mmc_roles AS mr ON mr.id = t.role_id
LEFT JOIN users AS u ON u.id = tl.user_id
LEFT JOIN communityuserdetails AS cud ON cud.user_id = u.id
LEFT JOIN banduserdetails AS bud ON bud.user_id = u.id
WHERE mmcs.user_type = 'mmc'
AND $rmCondition
AND $stageCondition
AND $mmcCondition
ORDER BY mmcs.id, t.stage_id, t.role_id, t.task_order
";
$pdo = new PDO(.....);
$stmt = $pdo->prepare($sql);
$rmId and $stmt->bindValue('rmId', $rmId); // (1)
$stage and $stmt->bindValue('stageId', $stage); // (2)
$mmcName and $stmt->bindValue('mmcName', $mmcName); // (3)
$stmt->execute();
return $stmt->fetchAll();
}
In lines marked (1), (2), and (3) you will see a way for conditional binding.
For simple queries I use ORM framework to reduce the need for building SQL manually.
It depends on a query size and difficulty.
I personally like heredocs. But I don't use it for a simple queries.
That is not important. The main thing is "Never forget to escape values"
You should always really really ALWAYS use prepare statements with place holders for your variables.
Its slightly more code, but it runs more efficiently on most DBs and protects you against SQL injection attacks.
I prefer as such:
$sql = "SELECT tbl1.col1, tbl1.col2, tbl2.col1, tbl2.col2"
. " FROM Table1 tbl1"
. " INNER JOIN Table2 tbl2 ON tbl1.id = tbl2.other_id"
. " WHERE tbl2.id = ?"
. " ORDER BY tbl2.col1, tbl2.col2"
. " LIMIT 10, 0";
It might take PHP a tiny bit longer to concatenate all the strings but I think it looks a lot nicer and is easier to edit.
Certainly for extremely long and specialized queries it would make sense to read a .sql file or use a stored procedure. Depending on your framework this could be as simple as:
$sql = (string) View::factory('sql/myfile');
(giving you the option to assign variables in the view/template if necessary). Without help from a templating engine or framework, you'd use:
$sql = file_get_contents("myfile.sql");
Hope this helps.
I normally write them as function argument:
db_exec ("SELECT ...");
Except cases when sql gonna be very large, I pass it as variable:
$SQL = "SELECT ...";
$result = db_exec ($SQL);
(I use wrapper-functions or objects for database operations)
$sql = sprintf("SELECT * FROM users WHERE id = %d", mysql_real_escape_string($_GET["id"]));
Safe from MySQL injection
You could use an ORM or an sql string builder, but some complex queries necessitate writing sql. When writing sql, as Michał Słaby illustrates, use query bindings. Query bindings prevent sql injection and maintain readability. As for where to put your queries: use model classes.
Once you get to a certain level, you realise that 99% of the SQL you write could be automated. If you write so much queries that you think of a properties file, you're probably doing something that could be simpler:
Most of the stuff we programmers do is CRUD: Create Read Update Delete
As a tool for myself, I built Pork.dbObject. Object Relation Mapper + Active Record in 2 simple classes (Database Abstraction + dbObject class)
A couple of examples from my site:
Create a weblog:
$weblog = new Weblog(); // create an empty object to work with.
$weblog->Author = 'SchizoDuckie'; // mapped internally to strAuthor.
$weblog->Title = 'A test weblog';
$weblog->Story = 'This is a test weblog!';
$weblog->Posted = date("Y-m-d H:i:s");
$weblog->Save(); // Checks for any changed values and inserts or updates into DB.
echo ($weblog->ID) // outputs: 1
And one reply to it:
$reply = new Reply();
$reply->Author = 'Some random guy';
$reply->Reply = 'w000t';
$reply->Posted = date("Y-m-d H:i:s");
$reply->IP = '127.0.0.1';
$reply->Connect($weblog); // auto-saves $reply and connects it to $weblog->ID
And, fetch and display the weblog + all replies:
$weblog = new Weblog(1); //Fetches the row with primary key 1 from table weblogs and hooks it's values into $weblog;
echo("<h1>{$weblog->Title}</h1>
<h3>Posted by {$weblog->Author} # {$weblog->Posted}</h3>
<div class='weblogpost'>{$weblog->Story}</div>");
// now fetch the connected posts. this is the real magic:
$replies = $weblog->Find("Reply"); // fetches a pre-filled array of Reply objects.
if ($replies != false)
{
foreach($replies as $reply)
{
echo("<div class='weblogreply'><h4>By {$reply->Author} # {$reply->Posted}</h4> {$reply->Reply}</div>");
}
}
The weblog object would look like this:
class Weblog extends dbObject
{
function __construct($ID=false)
{
$this->__setupDatabase('blogs', // database table
array('ID_Blog' => 'ID', // database field => mapped object property
'strPost' => 'Story', // as you can see, database field strPost is mapped to $this->Story
'datPosted' => 'Posted',
'strPoster' => 'Author',
'strTitle' => 'Title',
'ipAddress' => 'IpAddress',
'ID_Blog', // primary table key
$ID); // value of primary key to init with (can be false for new empty object / row)
$this->addRelation('Reaction'); // define a 1:many relation to Reaction
}
}
See, no manual SQL writing :)
Link + more examples: Pork.dbObject
Oh yeah i also created a rudimentary GUI for my scaffolding tool: Pork.Generator
I like this format. It was mentioned in a previous comment, but the alignment seemed off to me.
$query = "SELECT "
. " foo, "
. " bar "
. "FROM "
. " mytable "
. "WHERE "
. " id = $userid";
Easy enough to read and understand. The dots line up with the equals sign keeping everything in a clean line.
I like the idea of keeping your SQL in a separate file too, although I'm not sure how that would work with variables like $userid in my example above.