Simple way to read single record from MySQL - php

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.

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$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 :)

Related

How to grab an int from my MySQL server via PHP?

I am a novice when it comes to PHP but I don't understand if my syntax is wrong in this statement, or how would I grab an int from my MySQL server.
I know that my server credentials are working fine. How would I fix this statement to give me a returned integer of the number of reviews in the userinfo table?
$numberofpreviousreviews = mysql_query("SELECT `number_of_reviews` FROM `userinfo`") or die(mysql_error()); //Check to see how many reviews user has previously created
$amountofreviews = $numberofpreviousreviews + 1;
$query2 = mysql_query("ALTER TABLE userinfo ADD `amountofreviews` VARCHAR(10000)") or die(mysql_error()); //Make another column in database for the new review
You need to fetch your results after you run your query. There are several ways to do this but using mysql_fetch_assoc() will work for you.
$numberofpreviousreviews = mysql_query("SELECT `number_of_reviews` FROM `userinfo`") or die(mysql_error()); //Check to see how many reviews user has previously created
$row = mysql_fetch_assoc($numberofpreviousreviews);
$amountofreviews = $row['number_of_reviews'] + 1;
FYI, you shouldn't be using mysql_* functions anymore. They are deprecated and going away. You should use mysqli or PDO.
Assume you have a table userinfo which has the following structure and data :
Scenario #1 :
If you want to retrieve the all number_of_reviews, then do like this,
$query = "SELECT `number_of_reviews` FROM `userinfo`";
$result = mysqli_query($db,$query);
while ($row = mysqli_fetch_assoc($result)) {
echo "Number of reviews : " . $row['number_of_reviews'] . "<br/>";
}
It will give you,
Number of reviews : 20
Number of reviews : 40
Since, the result has many rows, it will display like above.
Scenario #2:
If you want to retrieve only the specific number_of_reviews for some user id (which is unique). I take id as 1 as a example here. Then do like,
$query2 = "SELECT `number_of_reviews` FROM `userinfo` WHERE `id` = 1";
$result2 = mysqli_query($db,$query2);
while ($row2 = mysqli_fetch_assoc($result2)) {
echo $row2['number_of_reviews'] . "<br/>";
}
This will print,
20.
Because, number_of_reviews is 20 for id 1.

How WHERE clause works when inserting php variables

I am having problems trying to get these queries with a WHERE clause to work. I have two tables which look like this :
What I am trying to do is return the genre that each film has. At the moment no data is returning at all from what I can see. Here are the two queries:
$film_id = $row_movie_list['film_id'];
mysql_select_db($database_fot , $fot);
$query_get_genre = "SELECT * FROM film_genre WHERE `id_film` ='". $film_id. "'";
$get_genre = mysql_query($query_get_genre, $fot) or die(mysql_error());
$row_get_genre = mysql_fetch_assoc($get_genre);
$totalRows_get_genre = mysql_num_rows($get_genre);
$genre_id = $row_get_genre['id_genre'];
mysql_select_db($database_fot , $fot);
$query_genre = "SELECT * FROM genre WHERE `id_genre` ='". $genre_id. "'";
$genre= mysql_query($query_genre, $fot) or die(mysql_error());
$row__genre = mysql_fetch_assoc($genre);
$totalRows_genre = mysql_num_rows($genre);
PHP with content area. I fairly new to PHP so any help would be appreciated.
<?php do { echo $genre['genre']; } while($row_get_genre = mysql_fetch_assoc($get_genre)); ?>
Update: I am now able to get first genre but not second it just echos the first one twice and I have tried but still no luck:
do {do { echo $row_genre['genre']; } while($row_genre = mysql_fetch_assoc($genre));} while($row_get_genre = mysql_fetch_assoc($get_genre)); ?>
Avoiding the fact that you're using a deprecated way to establish connection and interact with MySQL, what you're doing is getting a single relation genre-film and then getting the row of the genre that matches. You should surround part of your code with a while that executes while it's still genres of the film with id. Something like:
$film_id = $row_movie_list['film_id'];
mysql_select_db($database_fot , $fot);
$query_get_genre = "SELECT * FROM film_genre WHERE `id_film` ='". $film_id. "'";
$get_genre = mysql_query($query_get_genre, $fot) or die(mysql_error());
while($row_get_genre = mysql_fetch_assoc($get_genre)){
$genre_id = $row_get_genre['id_genre'];
$query_genre = "SELECT * FROM genre WHERE `id_genre` ='". $genre_id. "'";
$genre= mysql_query($query_genre, $fot) or die(mysql_error());
$row__genre = mysql_fetch_assoc($genre);
// You should do whatever you want to do with $row__genre here. Otherwise it will be cleared.
}
I must insist this is a deprecated and insecure way of communication with a MySQL Database. I recommend you read about MySQLi or PDO extensions.
MySQLi: http://www.php.net/manual/en/book.mysqli.php
PDO: http://www.php.net/manual/en/book.pdo.php

How to display field from MySQL?

I'm trying to display a field from my MySQL database. It's in the table tblproducts in the row with the id is set to 1. And under the column qty.
This is the code I'm using:
<?php
mysql_connect("localhost","username","password");
mysql_select_db("database_name");
$available = "SELECT qty FROM tblproducts WHERE id = 1";
$result = mysql_query($available);
echo $result;
?>
However, I keep getting this message: Resource id #2
I've done a bit of research and seen where other people are having similar problems but most of them are trying to display their data in an HTML table whereas I just need the data from 'qty' to display. And of course I'm definitely not a MySQL guru.
Can anyone help me out with this please?
Try changing this:
$result = mysql_query($available);
To this:
$result = mysql_result(mysql_query($available), 0);
Let's start from the start. (I'll assume you have the connection set)
Form the query
$query = "SELECT `qty`
FROM `tblproducts`
WHERE `id` = 1";
Execute the query
$run = mysql_query($query);
Now, put the result in an assoc array
$r = mysql_fetch_array($run);
See the contents of the array
echo $r['qty'];
It's also advised that you move up from mysql to either mysqli, or PDO. PDO is preferred as you're not bound to the MySQL database model.
Try this:
Here you need to generate associative array and then get the resulting row.
$query = "SELECT `qty` FROM `tblproducts` WHERE `id` = 1";
$run = mysql_query($query);
$r = mysql_fetch_array($run);
echo $r['qty'];
-
Thanks

how can i check if a variable is saved or not in the db?

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.

Question if my code is a low resources one

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).

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