I want only one single data from that DB but I am not able to "take it out of" $res.
$sql = "SELECT * FROM `study_stuffs_extra`.`tid` ORDER BY `id` DESC LIMIT 1 ";
$res = query($sql);
$tid = $res['tid'];
I have also tried a while loop to do so, but "couldn't do it". Is there any other method to "do it"?
try
$sql = "SELECT * FROM `study_stuffs_extra`.`tid` ORDER BY `id` DESC LIMIT 1 ";
$res = mysql_query($sql);
$res=mysql_fetch_array($res);
$tid = $res['tid'];
SELECT tid FROM study_stuffs_extra ORDER BY `id` DESC LIMIT 1
Also, check what query returns. Is that a mysql result? the whole result set? a row? Do some print_r to see what you get. Check for db errors after executing queries.
You may need to subscript the first member of $res, assuming it is an array.
$firstRow = $res[0];
Related
I am trying to retrieve the last ID from the database and increment it by one. My problem is that I am not able to retrieve it in a particular category. For instance, I have categories with a string value of A, B and C. The category with a string value of A will return only id starting from 1 as 10001, 10002 and the last ID to be retrieved is 10002 plus 1 so that the ID to be displayed is 10003.
Category "B" will return 20002 and category "C" will return 30002.
Here is my code:
<?php
$con = mysql_connect("server","username","password","db_name") or die (mysql_error());
mysql_select_db($con, 'db_name');
$sql = "Select `id` from `tbl_violation` WHERE `category` = 'A' ORDER BY `category` DESC LIMIT 1";
$result = mysql_query ($sql,$con);
while($row = mysql_fetch_array($result, $con))
{
$i = $row['id'];
$i++;
echo "DLR - " .$i;
}
?>
The error is this:
Warning: mysql_fetch_array() expects parameter 1 to be resource, boolean given in ...
Notice: Undefined variable: i in ...
First I must say again... Stay away from mysql_connect() and all other mysql_* functions. If you want a simple fix, just replace it with mysqli_ functions and make sure you escape ALL user provided input. A bit of reading But I would recommend to look into PDO.
That out of the way, your MYSQL problem is easy. You want to GROUP the elements so all the rows with same category column are groupped together and then select the maximum for each group. Your SQL would then be:
SELECT category, MAX(id) AS highest_id FROM tbl_violation GROUP BY category;
see this fiddle I made with a similar table.
You can then access the results you get from mysqli_query function the same way you do now...
while($row = mysqli_fetch_array($result, $con))
{
$i = $row['highest_id'];
$i++;
$category = $row['category'];
echo "$category - $i";
}
You can use SELECT MAX to get the highest id. I am assuming that id is not unique. If so, remove the WHERE statement from the query. Try the following.
<?php
$con = mysql_connect("server","username","password","db_name") or die (mysql_error());
mysql_select_db("database");
$sql = "Select MAX(`id`) from `tbl_violation` WHERE `category` = 'A";
$result = mysql_query ($sql,$con);
while($row = mysql_fetch_array($result))
{
$i = $row['id'];
echo "DLR - " .$i++;
}
?>
Also I would like to add that I agree with flynorc. Use PDO or mysqli.
Use
ORDER BY `id` DESC
Instead of
ORDER BY `category` DESC
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
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 .
What would be the most efficient way to SELECT this, then DELETE it immediately.
SELECT * from `usersOnline` WHERE timestamp>NOW()-INTERVAL 5 SECOND ORDER BY rand() LIMIT 1;
How could I take this same select query, but also make it delete what it selected in the most efficient way?
$query = 'SELECT * FROM `usersOnline` WHERE timestamp>NOW()-INTERVAL 5 SECOND ORDER BY rand() LIMIT 1;';
$result = mysql_query($query);
$record = mysql_fetch_assoc($result);
$query = 'DELETE FROM `usersOnline` WHERE id = ' . $record['id'];
mysql_query($query);
with mysql, you would have to do one and then the other. you would use the key from the select result to then delete that record directly afterwards. in this example, i am assuming your primary key column is named "id". you would replace the myssql functions with whichever method you are using to access the database of course.
you can do like this nested query
DELETE
FROM SomeTable
WHERE EXISTS
(SELECT * from `usersOnline` WHERE timestamp>NOW()-INTERVAL 5 SECOND ORDER BY rand() LIMIT 1;
)
thanks
use DELETE FROM: http://dev.mysql.com/doc/refman/5.0/en/delete.html
I know this example mixed prepared statments with regular statements. But it's up to the developer how to write the code. This is just a proof of concept, kept simple for easy reading.
$mysqli = new mysqli('localhost', 'user', 'password', 'userTable');
$result = $mysqli->query("SELECT * from `usersOnline` WHERE timestamp>NOW()-INTERVAL 5 SECOND ORDER BY rand() LIMIT 1");
$stmt = $mysqli->prepare("DELETE FROM 'usersOnline WHERE id = ?");
while ($row = mysql_fetch_assoc($result)) {
$stmt->bind_param('i', $row["id"]);
$stmt->execute();
}
$stmt->close();
$mysqli->close();
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 :)