I am trying to implement filters which will help users refine there search for other users. Here is an image of my search parameters just to provide you with a graphical representation of what I will soon convey:
There are three filters:
Gender
Age
Similarity in studies
By default, I want to convey all users on the system. So when a user goes onto users.php, every single user will be displayed, then, when the filters are applied, refine the results accordingly.
Not all three parameters have to be completed to start the search, for example, a user can simply search a female user and it should display all female users on search click.
I have tried to implement different queries for each scenario, but all users are always being displayed. If I specify I want to search for a female and then click search, it will do nothing, still showing me all users.
Also, I am struggling with the similarity in studies parameter. The way this works is that in a table called user_bio I am storing data regarding what the user is studying, the user can choose to not provide this information, so studying can also be empty in my table.
The way I want it to work is to look at what the logged in user is studying, and then find words which match in other peoples bio's. For example, I am currently logged in as Conor, and Conor is studying Computer Science. Ideally, an algorithm will run which searches other users bio from the user_bio table, and return all the users who have computer or science in their bio's. Im pretty sure this concerns the LIKE clause but I have never used it before so I cannot be certain.
Here is my current approach:
// processing filters
$refined_gender = htmlentities (strip_tags(#$_POST['gender']));
$age_from = htmlentities (strip_tags(#$_POST['age_from']));
$age_to = htmlentities (strip_tags(#$_POST['age_to']));
$studying = htmlentities (strip_tags(#$_POST['studying']));
$get_all_users = mysqli_query ($connect, "SELECT * FROM users" );
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
if (isset($_POST['submit'])){
// if gender parameter is used ...
if ($refined_gender){
$gender_statement = mysqli_prepare ($connect, "SELECT * FROM users WHERE gender = ?");
mysqli_stmt_bind_param($gender_statement, "s", $refined_gender);
mysqli_stmt_execute ($gender_statement);
mysqli_stmt_close($gender_statement);
}
// if studying parameter used...
if ($studying) {
// see explanation below...
}
// if gender and age parameter used...
if ($refined_gender && $age_from && $age_to){
$gen_and_age_statement = mysqli_prepare ($connect, "SELECT * FROM users WHERE gender = ? AND age BETWEEN ? AND ?");
mysqli_stmt_bind_param($gen_and_age_statement, "sss", $refined_gender, $age_from, $age_to);
mysqli_stmt_execute ($gen_and_age_statement);
mysqli_stmt_close($gen_and_age_statement);
}
}
Summary, what I need:
The SELECT * FROM users query to be executed by default on users.php. This will show all the users in the system.
For any filter to be applied. Not all filters need to be applied to get a result, a user can search for a female and click search, loading all female users in the system.
I need the query to change based on what filters have been applied. So if a user has searched for a male user, and the other two options are not selected, then query will be "SELECT * FROM users WHERE gender = '$var_here'.
Here iam providing code such that how can you write multiple filter option inside a single query..but here i didn't mention about your 3rd filter option studing,because its about another table and you were not mentioned it clearly such that it's linked to this table using foreign keys or following relational database structure.any way multi filter option is as follows..here i added database connect and escape injection's functions...if u don't need that neglect that part..
function escape($e_string)
{
global $connect;
if(!isset($connect))
{
// DATABASE CONNECTION QUERY
$connect = mysqli_connect("servername", "username", "password", "");
if (!$connect)
die("Connection failed: " . mysqli_connect_error());
}
$e_string = trim(utf8_encode($e_string));
$e_string = mysqli_real_escape_string($connect,$e_string);
return $e_string;
}
// processing filters
$refined_gender = isset($_POST['gender']) ? escape($_POST['gender']) : '';
$age_from = isset($_POST['age_from']) ? escape($_POST['age_from']) : '';
$age_to = isset($_POST['age_to']) ? escape($_POST['age_to']) : '';
$studying = isset($_POST['studying']) ? escape($_POST['studying']) : '';
$query = "SELECT * FROM users WHERE 1=1";
if (isset($_POST['submit'])){
$addstring1 = $addstring2 = $addstring3 = $and1 = $and2 = $and3 = "";
$andcnt =3;
if($refined_gender != '')
$addstring1 = " gender = '$refined_gender'";
if($age_from != '')
$addstring2 = " age >= '$age_from'";
if($age_to != '')
$addstring3 = " age <= '$age_to'";
for($i=1;$i<=$andcnt;$i++)
${"and".$i} = ${"addstring".$i} != '' ? " AND" : "";
$query .= $and1.$addstring1.$and2.$addstring2.$and3.$addstring3;
}
$get_all_users = mysqli_query ($connect, $query);
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
Instead of this code:
htmlentities (strip_tags(#$_POST['gender']));
you should validate it, like so:
$gender = filter_input(INPUT_POST, 'gender', FILTER_VALIDATE_REGEXP, ['options' => ['regexp' => '/^[mf]$/i']]);
$ageFrom = filter_input(INPUT_POST, 'age_from', FILTER_VALIDATE_INT, [ 'default' => 1, 'min_range' => 1, 'max_range' => 100]);
$ageTo = filter_input(INPUT_POST, 'age_to', FILTER_VALIDATE_INT, [ 'default' => 1, 'min_range' => 1, 'max_range' => 100]);
$studying = filter_input(INPUT_POST, 'gender', FILTER_VALIDATE_REGEXP, ['options' => ['regexp' => '/^(similar|different|same)$/i']]);
This is simpler and more secure.
Each input should be properly validated.
Avoid using #.
Once you have the values, you can concatenate them in to your query, like so:
$types = '';
$values = [];
$query = 'SELECT * FROM users';
$where = [];
// empty tests for both null (no data in input) and false (invalid data)
if (!empty($gender)) {
$where[] = 'gender = ?';
$types .= 's';
$values[] = &$gender;
}
if (!empty($ageFrom)) {
$where[] = 'age >= ?';
$types .= 'i';
$values = &$ageFrom;
}
if (!empty($ageTo)) {
$where[] = 'age <= ?';
$types .= 'i';
$values = &$ageTo;
}
if (!empty($studying)) {
$field = 'user_bio';
// Get the $user_bio value of the current user from the database
// Change the $user_bio into a regular expression collection of words
$regexp = '('.str_replace(' ','|',$user_bio).')';
// Set up the where
switch ($studying) {
case 'same':
$comparison = '= ?';
break;
case 'different':
$comparison = 'NOT REGEXP (?)';
break;
case 'similar':
$comparison = 'REGEXP (?)';
break;
}
$where[] = $field.' '.$comparison;
$types .= 's';
$values[] = &$user_bio;
}
if (count($where) > 0) {
$query .= ' WHERE '.implode(' AND ',$where);
}
// new mysqli ( host,
$mysqli = new mysqli('localhost','root','','stuff');
$stmt = $mysqli->prepare($query);
// This allows you to use a variable number of arguments with the prepared statement
// Note the use of the ampersands on the array assignment, this ensures they are passed by reference
$params = array_merge([$types],$values);
call_user_func_array([$stmt,'bind_param'],$params);
$stmt->execute();
// Bind a variable for each column
$stmt->bind_result($user_name);
while ($stmt->fetch()) {
var_dump($result);
}
(I'm not sure why the answers already provided don't address your question sufficiently.)
I'd approach it like this. First, get rid of that first query execution to pull all users. Instead, use just a single query.
Dynamically prepare the SQL text. Start the statement with the "SELECT ... FROM users". (We'll handle appending an ORDER BY as the last step.
I'd conditionally check each "filter", to see if I need to append a condition to the WHERE clause or not.
At the start of the SQL, we'll include a "WHERE 1=1".
$sql = "SELECT ... FROM users u"
$sql .= " WHERE 1=1";
The "WHERE 1=1" is basically useless. The optimizer is going to throw that away. The reason we add it is just to make our code easier later. We can just append our next filter with " AND condition", and not worry about whether this is the first one, and we need to use WHERE instead of AND.
We'll initialize a string and an array, to hold our bind types string "sssis" whatever it needs to be, and an array of references to the values we want to pass in.
$bind_type = "";
$bind_vals = array();
The processing for each filter is going to be icky... but we can do it. Check if we need to append anything to the SQL. If we do, figure out what needs to be added, including any bind placeholders. And append the type of the bind parameter ("i", "s", whatever) to the $bind_type string, and push (the reference to) a value into our $bind_vals array.
if ( $refined_gender ) {
// figure out what that SQL text needs to look like
// append the string to the SQL text
$sql .= " AND u.gender = ?";
// append type to string, and push a reference to the value into array
$bind_types .= "s";
$bind_val[] = &$refined_gender;
}
Our code in there is going to be more complicated than that. That's just handling an equality comparison. We're just keeping things simple now, to illustrate the pattern.
We repeat the same kind of thing for each filter we might need to add. Check if it's needed, figure out what we need to append to the SQL text, append to the bind_types string and push (a reference to) the value into the bind_vals array.
For working this out, I'd start with working on just one condition, and get that working, to get the kinks worked out. When we add more filters, and things go awry, I know where to look for the problem. (I know what was working before.)
When I'm done with the WHERE clause, I append any ORDER BY and LIMIT that I need. This could be conditional, but in the end, we're going to wind up doing something like this:
$sql .= " ORDER BY u.id DESC LIMIT 50";
When I'm done with all that, I've got a string containing SQL text that looks something like this:
SELECT ...
FROM users u
WHERE 1=1
AND u.gender = ?
AND u.age_from >= ?
AND u.age_to <= ?
ORDER BY u.id DESC
LIMIT 50
(in this example, it contains three bind placeholders. If we've done it right,
we'll have a $bind_types string containing three characters, e.g. "sii"
And we'll have a $bind_vals array that contains references to three values.
Now, we can call mysqli_stmt_prepare. If there's not an error in our SQL, we should get back a statement handle.
$stmt = mysqli_prepare($conn,$sql);
(Check the return from the prepare.)
Now we just need to bind our parameters. And this is where mysqli makes things a little hairy. If we were using PDO (or Perl DBI), calling the "bind parameter/bind value" would be easy. Those would let us pass an array of the bind values. But not mysqli. He won't let us call mysqli_stmt_bind_param with an array as an argument.
We need to run a function call like this:
mysqli_stmt_bind_param($stmt, $bind_types, &$refined_gender, &$age_from, ... );
And our problem is that we have a variable number of arguments.
There is a workaround.
We can use the call_user_func_array function.
Because the code is using procedural style and not object oriented style, the handle to the prepared statement is the first argument, the second argument is the bind types string, followed by the bind values. The bind values are already in an array. We just need to get all of those into one hugh jass array.
The array_merge function seems to be custom designed for doing this.
// array_merge(array($stmt), array($bind_types), $bind_vals)
That will return us a single array. Which is exactly what we need for calling the call_user_func_array function. We aren't going to need that array anywhere else (unless we're debugging, and we want to print it out).
We only need to call mysqli_stmt_bind_param if we have at least one bind placeholder in our statement. So we can shortcut around this if our $bind_types string is empty. (And we know $bind_types won't be "0" because our code never appended a "0" to it.)
if ($bind_types) {
call_user_func_array('mysqli_stmt_bind_param', array_merge(array($stmt), array($bind_types), $bind_vals) );
}
The first argument (to call_user_func_array) is the name of the function we want to execute, and the second argument is the hugh jass array that we want converted into a list.
And the whole point of doing that is making it dynamic, we can pass in one, two, three, bind values.
At this point, we're ready to execute the statement, and fetch the results.
Again, important to point out: mysqli_stmt_bind_param expects the bind values to be passed by reference, not by value. And that's why we pushed references to the values into the bind_vals array.
I'm not sure what question you asked.
But definitely ditch that first call to mysqli_query. That's going to return all rows in the users table.
With one or two conditions, the approach of static SQL and static bind types, and listing out the bind values is workable.
But when we get three, four, five possible filters, and all the possible combinations, that's going to be unweildy.
So we go with a more dynamic approach, dynamically creating the query, and pushing our bind values on an array as go.
This Html page:
<form method="POST" action="">
<input type="radio" name="rbo_gender" value="male">Male
<input type="radio" name="rbo_gender" value="female">Female
Age From<select name="agefrom">
<?php
for($i=10;$i<50;$i++):
?>
<option value="<?php echo $i?>"><?php echo $i?></option>
<?php
endfor;
?>
</select>
Age To<select name="ageto">
<?php
for($i=10;$i<50;$i++):
?>
<option value="<?php echo $i?>"><?php echo $i?></option>
<?php
endfor;
?>
</select>
Studying:
<input type="radio" name="rbo_type" value="similar">Similar
<input type="radio" name="rbo_type" value="exact">Exactly same
<input type="radio" name="rbo_type" value="different">Different
<input type="submit" name="btnsearch" value="Search">
</form>
This is php part:
if($_POST["btnsearch"])
{
if(!empty($_POST["rbo_gender"]))
{
$gender = $_POST["rbo_gender"];
$cond .= " and gender = '".$gender."'";
}
if(!empty($_POST["agefrom"]))
{
$agefrom = $_POST["agefrom"];
$cond .= " and age >= '".$agefrom."'";
}
if(!empty($_POST["ageto"]))
{
$ageto = $_POST["ageto"];
$cond .= " and age <= '".$ageto."'";
}
if(!empty($_POST["rbo_type"]))
{
$user_type = $_POST["rbo_type"];
switch($_POST["rbo_type"])
{
case "similar": $cond .= " and user_bio like '%".$ageto."%'";
break;
case "exact": $cond .= " and user_bio = '".$ageto."'";
break;
case "different":$cond .= " and user_bio ! like '%".$ageto."%'";
break;
}
}
$query = "select * from users where 1 ".$cond;
}
Please update query as per mysqli() & use bind param. Also instead of use # try to use filter_input you can use REGEXP instead of like also. I have created the variable to use bind_param purpose.
I have pre parameters determining what is passed into my query. In one case I want to search for ALL UUIDs, and in another case I want to search for specific UUID numbers. I would like to do this in one query statement instead of breaking it into two seperate calls (like below)
example 1:
$uuidtosearchfor = "1234";
$query = "SELECT ID,name,UUID FROM table where active = 1 AND UUID ='$uuidtosearchfor'";
exmaple 2:
$query = "SELECT ID,name,UUID FROM table where active = 1";
so instead I want this:
if(rule1)
$uuidtosearchfor = "*"; // return everything
else
$uuidtosearchfor = "2134"; // return everything
$query = "SELECT ID,name,UUID FROM table where active = 1 AND UUID = '$uuidtosearchfor' ";
If you use LIKE instead of =, you can use % as wildcard. But LIKE isn't exactly the same as =.
With = you could construct the query as UUID=UUID. The downside is, you cannot use prepared statements and have to take care about escaping the parameter yourself.
Actually, I don't see how any of these makes your life easier. I'd rather construct the query such that the condition is not added if you want to match all uuids.
I'm using Postgresql 9.2 and PHP 5.5 on Linux. I have a database with "patient" records in it, and I'm displaying the records on a web page. That works fine, but now I need to add interactive filters so it will display only certain types of records depending on what filters the user engages, something like having 10 checkboxes from which I build an ad-hoc WHERE clause based off of that information and then rerun the query in realtime. I'm a bit unclear how to do that.
How would one approach this using PHP?
All you need to do is recieve all the data of your user's selected filters with $_POST or $_GET and then make a small function with a loop to concatenate everything the way your query needs it.
Something like this... IN THE CASE you have only ONE field in your DB to match with. It's a simple scenario and with more fields you'll need to make it so that you add the field you really need in each case, nothing too complex.
<?php
//recieve all the filters and save them in array
$keys[] = isset($_POST['filter1'])?'$_POST['filter1']':''; //this sends empty if the filter is not set.
$keys[] = isset($_POST['filter2'])?'$_POST['filter2']':'';
$keys[] = isset($_POST['filter3'])?'$_POST['filter3']':'';
//Go through the array and concatenate the string you need. Of course, you might need AND instead of OR, depending on what your needs are.
foreach ($keys as $id => $value) {
if($id > 0){
$filters.=" OR ";
}
$filters.=" your_field = '".$value."' ";
}
//at this point $filters has a string with all your
//Then make the connection and send the query. Notice how the select concatenates the $filters variable
$host = "localhost";
$user = "user";
$pass = "pass";
$db = "database";
$con = pg_connect("host=$host dbname=$db user=$user password=$pass")
or die ("Could not connect to server\n");
$query = "SELECT * FROM table WHERE ".$filters;
$rs = pg_query($con, $query) or die("Cannot execute query: $query\n");
while ($row = pg_fetch_row($rs)) {
echo "$row[0] $row[1] $row[2]\n";
//or whatever way you want to print it...
}
pg_close($con);
?>
The above code will get variables from a form that sent 3 variables (assuming all of them correspond to the SAME field in your DB, and makes a string to use as your WHERE clause.
If you have more than one field of your db to filter through, all you need to do is be careful on how you match the user input with your fields.
NOTE: I did not add it here for practical reasons... but please, please sanitize user input.. ALWAYS sanitize user input before using user controlled data in your queries.
Good luck.
Don't do string concatenation. Once you have the values just pass them to the constant query string:
$query = "
select a, b
from patient
where
($x is not null and x = $x)
or
('$y' != '' and y = '$y')
";
If the value was not informed by the user pass it as null or empty. In the above query the x = $x condition will be ignored if $x is null and the y = '$y' condition will be ignored if $y is empty.
With that said, a check box will always be either true or false. What is the exact problem you are facing?
Always sanitize the user input or use a driver to do it for you!
I have created a Where clause builder exactly for that purpose. It comes with the Pomm project but you can use it stand alone.
<?php
$where = Pomm\Query\Where::create("birthdate > ?", array($date->format('Y-m-d')))
->andWhere('gender = ?', array('M'));
$where2 = Pomm\Query\Where::createWhereIn('something_id', array(1, 15, 43, 104))
->orWhere($where);
$sql = sprintf("SELECT * FROM my_table WHERE %s", $where2);
$statement = $pdo->prepare($sql);
$statement->bind($where2->getValues());
$results = $statement->execute();
This way, your values are escaped and you can build dynamically your where clause. You will find more information in Pomm's documentation.
I have a sql query that is generated using php. It returns the surrogate key of any record that has fields matching the search term as well as any record that has related records in other tables matching the search term.
I join the tables into one then use a separate function to retrieve a list of the columns contained in the tables (I want to allow additions to tables without re-writing php code to lower ongoing maintenance).
Then use this code
foreach ($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". $qry_string)
I'm trying to write a simple, full text search with PHP and PDO. I'm not quite sure what the best method is to search a DB via SQL and PDO. I found this this script, but it's old MySQL extension. I wrote this function witch should count the search matches, but the SQL is not working. The incoming search string look like this: 23+more+people
function checkSearchResult ($searchterm) {
//globals
global $lang; global $dbh_pdo; global $db_prefix;
$searchterm = trim($searchterm);
$searchterm = explode('+', $searchterm);
foreach ($searchterm as $value) {
$sql = "SELECT COUNT(*), MATCH (article_title_".$lang.", article_text_".$lang.") AGINST (':queryString') AS score FROM ".$db_prefix."_base WHERE MATCH (article_title_".$lang.", article_text_".$lang.") AGAINST ('+:queryString')";
$sth = $dbh_pdo->prepare($sql);
$sql_data = array('queryString' => $value);
$sth->execute($sql_data);
echo $sth->queryString;
$row = $sth->fetchColumn();
if ($row < 1) {
$sql = "SELECT * FROM article_title_".$lang." LIKE :queryString OR aricle_text_".$lang." LIKE :queryString";
$sth = $dbh_pdo->prepare($sql);
$sql_data = array('queryString' => $value);
$sth->execute($sql_data);
$row = $sth->fetchColumn();
}
}
//$row stays empty - no idea what is wrong
if ($row > 1) {
return true;
}
else {
return false;
}
}
When you prepare the $sql_data array, you need to prefix the parameter name with a colon:
array('queryString' => $value);
should be:
array(':queryString' => $value);
In your first SELECT, you have AGINST instead of AGAINST.
Your second SELECT appears to be missing a table name after FROM, and a WHERE clause. The LIKE parameters are also not correctly formatted. It should be something like:
sql = "SELECT * FROM ".$db_prefix."_base WHERE article_title_".$lang." LIKE '%:queryString%' OR aricle_text_".$lang." LIKE '%:queryString%'";
Update 1 >>
For both SELECT statements, you need unique identifiers for each parameter, and the LIKE wildcards should be placed in the value, not the statement. So your second statement should look like this:
sql = "SELECT * FROM ".$db_prefix."_base WHERE article_title_".$lang." LIKE :queryString OR aricle_text_".$lang." LIKE :queryString2";
Note queryString1 and queryString2, without quotes or % wildcards. You then need to update your array too:
$sql_data = array(':queryString1' => "%$value%", ':queryString2' => "%$value%");
See the Parameters section of PDOStatement->execute for details on using multiple parameters with the same value. Because of this, I tend to use question marks as placeholders, instead of named parameters. I find it simpler and neater, but it's a matter of choice. For example:
sql = "SELECT * FROM ".$db_prefix."_base WHERE article_title_".$lang." LIKE ? OR aricle_text_".$lang." LIKE ?";
$sql_data = array("%$value%", "%$value%");
<< End of Update 1
I'm not sure what the second SELECT is for, as I would have thought that if the first SELECT didn't find the query value, the second wouldn't find it either. But I've not done much with MySQL full text searches, so I might be missing something.
Anyway, you really need to check the SQL, and any errors, carefully. You can get error information by printing the results of PDOStatement->errorCode:
$sth->execute($sql_data);
$arr = $sth->errorInfo();
print_r($arr);
Update 2 >>
Another point worth mentioning: make sure that when you interpolate variables into your SQL statement, that you only use trusted data. That is, don't allow user supplied data to be used for table or column names. It's great that you are using prepared statements, but these only protect parameters, not SQL keywords, table names and column names. So:
"SELECT * FROM ".$db_prefix."_base"
...is using a variable as part of the table name. Make very sure that this variable contains trusted data. If it comes from user input, check it against a whitelist first.
<< End of Update 1
You should read the MySQL Full-Text Search Functions, and the String Comparison Functions. You need to learn how to construct basic SQL statements, or else writing even a simple search engine will prove extremely difficult.
There are plenty of PDO examples on the PHP site too. You could start with the documentation for PDOStatement->execute, which contains some examples of how to use the function.
If you have access to the MySQL CLI, or even PHPMyAdmin, you can try out your SQL without all the PHP confusing things. If you are going to be doing any database development work as part of your PHP application, you will find being able to test SQL independently of PHP a great help.