$category = htmlspecialchars($_GET['category']);
$sql = "(SELECT number
FROM german
WHERE german.category_german LIKE ".$category."
ORDER BY number DESC
LIMIT 1) as 'high',
(SELECT number
FROM german
WHERE german.category_german LIKE ".$category."
ORDER BY number ASC
LIMIT 1) as 'low'";
if ($result = $conn -> query($sql)) {
while ($row = $result -> fetch_row()) {
$high_value = $row[high];
$low_value = $row[low];
$r_n = rand($low_value,$high_value).PHP_EOL;
echo $r_n;
}
}
What am I missing? I want the highest and the lowest value of a table, why can't I save that value in PHP? I just can't access the values. And I tried out MIN and MAX as well, but they didn't function neither:
$category = htmlspecialchars($_GET['category']);
$sql = "SELECT MIN('number') AS 'low', MAX('number') AS 'high' FROM german WHERE german.category_german LIKE ".$category."";
if ($result = $conn -> query($sql)) {
while ($row = $result -> fetch_row()) {
$high_value = $row[high];
$low_value = $row[low];
$r_n = rand($low_value,$high_value).PHP_EOL;
echo $r_n;
}
}
As a result of $r_n I only get 0. The database shouldn't be the problem. Beforehand (where I only used the highest value) everything functioned:
$category = htmlspecialchars($_GET['category']);
$sql = "SELECT number FROM german WHERE german.category_german LIKE ".$category." ORDER BY number DESC LIMIT 1";
if ($result = $conn -> query($sql)) {
while ($row = $result -> fetch_row()) {
$r_n = $row[0];
$r_n = rand(1,$r_n).PHP_EOL;
echo $r_n;
}
}
You can't use multiple SELECT statements at top-level of a query. They would have to be subqueries:
SELECT (SELECT ...) AS high, (SELECT ...) AS low
Your second query would have worked, but you shouldn't have quotes around number. That makes it a literal string, not the column values. So MAX('number') should be MAX(number), MIN('number') should be MIN(number). See When to use single quotes, double quotes, and backticks in MySQL
And if category is a string, you need to put quotes around $category:
WHERE german.category_german LIKE '".$category."'"
But the better way to resolve that problem is to use a prepared statement with parameters, How can I prevent SQL injection in PHP? than substituting variables directly into the query. See
I am trying to pass a variable to a very basic mysql query. but php doesnt return a true value. nothing.
i have checked everything
the problem is here.
the syntax of $a varible typing into mysql query
$result = mysql_query("SELECT id,floatingnumber FROM posts WHERE id='$a' LIMIT 1");
when i change $a to 22 it returns a value otherwise nothing.
exact query is here...
$a=$this->post_id;
$result = mysql_query('SELECT floatingnumber FROM posts WHERE id="'.$a.'" LIMIT 1')or die(mysql_error());
$row = mysql_fetch_row($result);
$sdfa=$a.'-'.$row[0];
$sdfa returns "86 - " without quotes 86 - space
so the problem is on the mysql fetch row please help
Have you tried echoing the query to see what the real value of $a is?
echo "SELECT id,floatingnumber FROM posts WHERE id='$a' LIMIT 1";
Have you tried checking for errors?
$result = mysql_query("SELECT id,floatingnumber FROM posts WHERE id='$a' LIMIT 1") or die(mysql_error());
Also, you shouldn't even be using mysql_* as it's deprecated.
This is how you'd do it in PDO:
$stmnt = $db->prepare("SELECT id,floatingnumber FROM posts WHERE id=:id LIMIT 1");
$stmnt->bindValue( ':id' , $a , PDO::PARAM_INT );
$stmnt->execute();
$result = $stmnt->fetchAll(PDO::FETCH_ASSOC);
typically when I'm writing in double quotes, simply putting in the variable works:
"... $1 ..."
but also, I originally learned it with brackets
"... {$1} ..."
you can try that. also, a handy way to write queries is store the query string in its own variable so you can easily print out the query and see what you wrote before submitting.
$query = "SELECT id,floatingnumber FROM posts WHERE id=$a LIMIT 1";
$result = mysql_query( $query );
This helps identify things like this.
try this
$result = mysql_query("SELECT id,floatingnumber FROM posts WHERE id='".$a."' LIMIT 1");
if your $a is a number then do like that
$result = mysql_query("SELECT id,floatingnumber FROM posts WHERE id= $a LIMIT 1");
EDIT :
your code is right
$row = mysql_fetch_row($result);
$sdfa=$a.'-'.$row[0];
the problem is in your sql or table because there is no floatingnumber where id is 86 .
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.
Hi please tell me if this is a low resources piece of code, and if it is not how shall I change it ? Thank you!
$query = 'SELECT MAX(ID) as maxidpost
FROM wp_posts';
$result = mysql_query($query) or die(mysql_error());
while($row = mysql_fetch_array($result)) {
$postid = $row['maxidpost']+1;
echo "p=$postid";
The improvement is debatable, but:
$query = 'SELECT MAX(ID) +1 as maxidpost
FROM wp_posts';
$result = mysql_query($query) or die(mysql_error());
while($row = mysql_fetch_array($result)) {
echo "p = ". $row["maxidpost"];
You can do math in SQL statements, saving you from having to do the operation in PHP.
It'd be nice to know what you're using this for - if it's the next id to be inserted, using AUTO_INCREMENT would be safer. SELECT statements are generally given higher priority over INSERT/UPDATE/DELETE, and thus can read before an insert from another source -- which would risk duplicates.
Because you are returning one row, you should do something like:
$query = 'SELECT MAX(ID) as maxidpost FROM wp_posts';
$result = mysql_query($query) or die(mysql_error());
$row = mysql_fetch_row($result);
$postid = $row['maxidpost']+1;
echo "p=$postid";
Otherwise seems about as good as you could do.
You can recalculate the post code after each post. Start with zero. Select it from the database, use that id, add one, save back to database.
Or you could use auto increment (if that is possible).
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 :)