This is what i am trying right now but no luck
$bid = $next - 2;//This subtracts 2 from the number, this number is also auto generated
$preid = $bid;
$query = "SELECT * FROM images where imageid = '$preid'";
$sql = mysqli_query($conn,$query) or die(mysqli_error($conn));
while(mysqli_num_rows($sql) !=0) {
$select_query = "SELECT * FROM images where imageid = '$preid'";
$sql = mysqli_query($conn,$select_query) or die(mysqli_error($conn));
--$preid;
}
whats suppose to happen is that if a record does not exist it subtracts 1 from preid and runs the query again with the new preid and keeps happening until a record it found but cant figure out how to do it.
I am assuming that you are constantly checking database for new values. However, on a large scale application thi is an highly inefficient way to constantly ping the database.
You have made a variable $preid but you are not using it anywhere.
This is how i would do it if i were to go according to your way
$bid = $next - 2;//This subtracts 2 from the number, this number is also auto generated
$preid = $bid;
$query = "SELECT * FROM images where imageid = '$preid'";
$sql = mysqli_query($conn,$query) or die(mysqli_error($conn));
while(mysqli_num_rows($sql) !=0 || !$preid) { //notice here i added the condition for preid.
$select_query = "SELECT * FROM images where imageid = '$preid'";
$sql = mysqli_query($conn,$select_query) or die(mysqli_error($conn));
--$preid;
}
now what happens is that the loop will run as long as either of the two condition stays true ie either a row is returned from the database or it will keep searching until preid is not 0.
If you want to test for an empty set, your while should run while mysqli_num_rows == 0
while(mysqli_num_rows($sql) == 0) {
$select_query = "SELECT * FROM images where imageid = '$preid'";
$sql = mysqli_query($conn,$select_query) or die(mysqli_error($conn));
$preid--;
}
As #DarkBee has mentionend in his comment, this code is highly vulnerable for an infinite loop which will take down your script, as soon as there are no entries for anything.
Related
Basically, I have been having some trouble with sending a request to a MySQL server and receiving the data back and checking if a user is an Admin or just a User.
Admin = 1
User = 0
<?php
$checkAdminQuery = "SELECT * FROM `users` WHERE `admin`";
$checkAdmin = $checkAdminQuery
mysqli_query = $checkAdmin;
if ($checkAdmin == 1) {
echo '<h1>Working!</h1>';
}else {
echo '<h1>Not working!</h1>';
}
?>
Sorry that this may not be as much info needed, I am currently new to Stack Overflow.
Firstly, your SQL query is wrong
SELECT * FROM `users` WHERE `admin`
It's missing the rest of the WHERE clause
SELECT * FROM `users` WHERE `admin` = 1
Then you're going to need fetch the result from the query results. You're not even running the query
$resultSet = mysqli_query($checkAdminQuery)
Then from there, you'll want to extract the value.
while($row = mysqli_fetch_assoc($resultSet))
{
//do stuff
}
These are the initial problems I see, I'll continue to analyze and find more if needed.
See the documentation here
http://php.net/manual/en/book.mysqli.php
You need to have something like user id if you want to check someone in database. For example if you have user id stored in session
<?php
// 1. start session
session_start();
// 2. connect to db
$link = mysqli_connect('host', 'user', 'pass', 'database');
// 3. get user
$checkAdminQuery = mysqli_query($link, "SELECT * FROM `users` WHERE `id_user` = " . $_SESSION['id_user'] );
// 4. fetch from result
$result = mysqli_fetch_assoc($checkAdminQuery);
// 5. if column in database is called admin test it like this
if ($result['admin'] == 1) {
echo '<h1>Is admin!</h1>';
}else {
echo '<h1>Not working!</h1>';
}
?>
// get all admin users (assumes database already connected)
$rtn = array();
$checkAdminQuery = "SELECT * FROM `users` WHERE `admin`=1";
$result = mysqli_query($dbcon,$checkAdminQuery) or die(mysqli_error($dbconn));
while($row = mysqli_fetch_array($result)){
$rtn[] = $row;
}
$checkAdminQuery = "SELECT * FROM `users` WHERE `admin`"; !!!!
where what ? you need to specify where job = 'admin' or where name ='admin'
you need to specify the column name where you are adding the admin string
I am using if else condition with foreach loop to check and insert new tags.
but both the conditions(if and alse) are being applied at the same time irrespective of wether the mysql found id is equal or not equal to the foreach posted ID. Plz help
$new_tags = $_POST['new_tags']; //forget the mysl security for the time being
foreach ($new_tags as $fnew_tags)
{
$sqlq = mysqli_query($db3->connection, "select * from o4_tags limit 1");
while($rowq = mysqli_fetch_array($sqlq)) {
$id = $rowq['id'];
if($id == $fnew_tags) { //if ID of the tag is matched then do not insert the new tags but only add the user refrence to that ID
mysqli_query($db3->connection, "insert into user_interests(uid,tag_name,exp_tags) values('$session->userid','$fnew_tags','1')");
}
else
{ //if ID of the tag is not matched then insert the new tags as well as add the user refrence to that ID
$r = mysqli_query($db3->connection, "insert into o4_tags(tag_name,ug_tags,exp_tags) values('$fnew_tags','1','1')");
$mid_ne = mysqli_insert_id($db3->connection);
mysqli_query($db3->connection, "insert into user_interests(uid,tag_name,exp_tags) values('$session->userid','$mid_ne','1')");
}
}
}
i think you are inserting
$r = mysqli_query($db3->connection, "insert into o4_tags(tag_name,ug_tags,exp_tags)
values('$fnew_tags','1','1')");$mid_ne = mysqli_insert_id($db3->connection);
and then you are using while($rowq = mysqli_fetch_array($sqlq))
which now has records you just inserted therefore your if is executed
I'm pretty sure the select query below will always return the same record.
$sqlq = mysqli_query($db3->connection, "select * from o4_tags limit 1");
I think most of the time it will goes to the else, which execute the 2 insert.
Shouldn't you write the query like below?
select * from o4_tags where id = $fnew_tags limit 1
At the moment im sending scores and data to my database from my flash game, though every level completed is a new record.
feilds are set out like l1Score,l2Score,l3Score
im trying to figure out how to update records if the field ipAddress and playerName match the current $varibles.
UPDATE highscores SET l2Score = '$l2Score' WHERE ipAddress = "$ipAddress" && playerName = '$playerName'
I was thinking somthing along these lines, but could someone point me in the right direction please!
First you want to perform a query to check if there is already a score in place for that user & IP.
$sql = "SELECT * FROM highscores WHERE ipAdress = '$ipAdress' AND playerName = '$playerName'";
$result = mysql_query($sql, $con);
$row = mysql_fetch_assoc($result);
Now, if $row is empty then you want to insert a new record, else you want to update a previous record.
if($row == "")
{
$query = "INSERT INTO highscores (l2score, ipAdress, playerName) VALUES ('$l2score', '$ipAdress', '$playerName'";
} else {
$query = "UPDATE highscores SET l2Score = '$l2Score' WHERE ipAdress = '$ipAdress' AND playerName = '$playerName'";
You may need to edit this to fit with the specific query that you need.
I have this code:
$local_id = $_GET['id'];
$sql = dbquery("SELECT * FROM `videos` WHERE `id` = ".$local_id." LIMIT 0, 1");
while($row = mysql_fetch_array($sql)){
$video_id = $row["youtube_id"];
// the rest
}
how can i check if $local_id does not exist in the db and display an error?
mysql_num_rows
if(mysql_num_rows($sql) == 0) {
//Show error
}
$sql = dbquery("select count(*) from videos where id = ".$local_id." LIMIT 0, 1");
$row = mysql_fetch_row($sql);
if($row[0] == 0)
echo 'error';
You can use the following query:
"SELECT COUNT(*) FROM `videos` WHERE `id` = ".mysql_real_escape_string($local_id)
This query will return one number: how many records have matched your query. If this is zero, you surely know that there are no records with this ID.
This is more optimal than other solutions posted in case you only want to check for the existence of the ID, and don't need the data (if you use SELECT * ..., all the data will be unnecessarily sent from MySQL to you). Otherwise mysql_num_rows() is the best choice, as #Ryan Doherty correctly posted.
Be sure to ALWAYS escape data that came from the outside (this time GET) before you put it into a query (mysql_real_escape_string() for MySQL).
If you fail to do so, you are a possible victim for SQL Injection.
You could have a $count variable and increment it in the while loop. After the loop, check the count, if it is 0, then echo an error message.
What's the best way with PHP to read a single record from a MySQL database? E.g.:
SELECT id FROM games
I was trying to find an answer in the old questions, but had no luck.
This post is marked obsolete because the content is out of date. It is not currently accepting new interactions.
$id = mysql_result(mysql_query("SELECT id FROM games LIMIT 1"),0);
$link = mysql_connect('localhost','root','yourPassword')
mysql_select_db('database_name', $link);
$sql = 'SELECT id FROM games LIMIT 1';
$result = mysql_query($sql, $link) or die(mysql_error());
$row = mysql_fetch_assoc($result);
print_r($row);
There were few things missing in ChrisAD answer. After connecting to mysql it's crucial to select database and also die() statement allows you to see errors if they occur.
Be carefull it works only if you have 1 record in the database, because otherwise you need to add WHERE id=xx or something similar to get only one row and not more. Also you can access your id like $row['id']
Using PDO you could do something like this:
$db = new PDO('mysql:host=hostname;dbname=dbname', 'username', 'password');
$stmt = $db->query('select id from games where ...');
$id = $stmt->fetchColumn(0);
if ($id !== false) {
echo $id;
}
You obviously should also check whether PDO::query() executes the query OK (either by checking the result or telling PDO to throw exceptions instead)
Assuming you are using an auto-incrementing primary key, which is the normal way to do things, then you can access the key value of the last row you put into the database with:
$userID = mysqli_insert_id($link);
otherwise, you'll have to know more specifics about the row you are trying to find, such as email address. Without knowing your table structure, we can't be more specific.
Either way, to limit your SELECT query, use a WHERE statement like this:
(Generic Example)
$getID = mysqli_fetch_assoc(mysqli_query($link, "SELECT userID FROM users WHERE something = 'unique'"));
$userID = $getID['userID'];
(Specific example)
Or a more specific example:
$getID = mysqli_fetch_assoc(mysqli_query($link, "SELECT userID FROM users WHERE userID = 1"));
$userID = $getID['userID'];
Warning! Your SQL isn't a good idea, because it will select all rows (no WHERE clause assumes "WHERE 1"!) and clog your application if you have a large number of rows. (What's the point of selecting 1,000 rows when 1 will do?) So instead, when selecting only one row, make sure you specify the LIMIT clause:
$sql = "SELECT id FROM games LIMIT 1"; // Select ONLY one, instead of all
$result = $db->query($sql);
$row = $result->fetch_assoc();
echo 'Game ID: '.$row['id'];
This difference requires MySQL to select only the first matching record, so ordering the table is important or you ought to use a WHERE clause. However, it's a whole lot less memory and time to find that one record, than to get every record and output row number one.
One more answer for object oriented style. Found this solution for me:
$id = $dbh->query("SELECT id FROM mytable WHERE mycolumn = 'foo'")->fetch_object()->id;
gives back just one id. Verify that your design ensures you got the right one.
First you connect to your database. Then you build the query string. Then you launch the query and store the result, and finally you fetch what rows you want from the result by using one of the fetch methods.
$link = mysql_connect('localhost','root','yourPassword')
mysql_select_db('database',$link);
$sql = 'SELECT id FROM games'
$result = mysql_query($sql,$link);
$singleRow = mysql_fetch_array($result)
echo $singleRow;
Edit: So sorry, forgot the database connection. Added it now
'Best way' aside some usual ways of retrieving a single record from the database with PHP go like that:
with mysqli
$sql = "SELECT id, name, producer FROM games WHERE user_id = 1";
$result = $db->query($sql);
$row = $result->fetch_row();
with Zend Framework
//Inside the table class
$select = $this->select()->where('user_id = ?', 1);
$row = $this->fetchRow($select);
The easiest way is to use mysql_result.
I copied some of the code below from other answers to save time.
$link = mysql_connect('localhost','root','yourPassword')
mysql_select_db('database',$link);
$sql = 'SELECT id FROM games'
$result = mysql_query($sql,$link);
$num_rows = mysql_num_rows($result);
// i is the row number and will be 0 through $num_rows-1
for ($i = 0; $i < $num_rows; $i++) {
$value = mysql_result($result, i, 'id');
echo 'Row ', i, ': ', $value, "\n";
}
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$db = new mysqli('localhost', 'tmp', 'tmp', 'your_db');
$db->set_charset('utf8mb4');
if($row = $db->query("SELECT id FROM games LIMIT 1")->fetch_row()) { //NULL or array
$id = $row[0];
}
I agree that mysql_result is the easy way to retrieve contents of one cell from a MySQL result set. Tiny code:
$r = mysql_query('SELECT id FROM table') or die(mysql_error());
if (mysql_num_rows($r) > 0) {
echo mysql_result($r); // will output first ID
echo mysql_result($r, 1); // will ouput second ID
}
Easy way to Fetch Single Record from MySQL Database by using PHP List
The SQL Query is SELECT user_name from user_table WHERE user_id = 6
The PHP Code for the above Query is
$sql_select = "";
$sql_select .= "SELECT ";
$sql_select .= " user_name ";
$sql_select .= "FROM user_table ";
$sql_select .= "WHERE user_id = 6" ;
$rs_id = mysql_query($sql_select, $link) or die(mysql_error());
list($userName) = mysql_fetch_row($rs_id);
Note: The List Concept should be applicable for Single Row Fetching not for Multiple Rows
Better if SQL will be optimized with addion of LIMIT 1 in the end:
$query = "select id from games LIMIT 1";
SO ANSWER IS (works on php 5.6.3):
If you want to get first item of first row(even if it is not ID column):
queryExec($query) -> fetch_array()[0];
If you want to get first row(single item from DB)
queryExec($query) -> fetch_assoc();
If you want to some exact column from first row
queryExec($query) -> fetch_assoc()['columnName'];
or need to fix query and use first written way :)