Find a next record after disabling a record? - php

I have a created a function changeIp() to disabled a record and return a new record. As you can see I am using 3 SQL query.
Is there a better way doing to reduce number of SQL queries?
function changeIp() {
// Find 1 record which is not disabled
$SQL = "SELECT * FROM ip WHERE disable = 0 order by id limit 1";
$qIp = mysql_query($SQL) or die(mysql_error());
$qrow = mysql_fetch_assoc($qIp);
// Disable a record
$id = $qrow['id'];
$SQL = "UPDATE ip set disable = 1 WHERE id = $id";
mysql_query($SQL) or die(mysql_error());
// Return the next record
$SQL = "SELECT * FROM ip WHERE disable = 0 order by id limit 1";
$qIp = mysql_query($SQL) or die(mysql_error());
$qrow = mysql_fetch_assoc($qIp);
return $qrow['ip'];
}

You should use "mysqli" or php, but that is a separate matter from your question.
Your queries are fine. You can't really do an update and select in a single statement. You can improve performance with an index on ip(id, disable). And, an index on ip(disable, id) might also be beneficial, depending on a number of factors.

Related

How to do two DB queries at once in PHP?

I have two queries but can I have them as just one
$sql = ("SELECT * FROM table WHERE title='$title' LIMIT 1");
$sql = ("UPDATE table SET views = views+1 where title='$title' ");
$query = mysql_query($sql) or die("Error Connecting To db");
At the moment the 2nd one works but not the first one.
This is your code:
$sql = ("SELECT * FROM table WHERE title='$title' LIMIT 1");
$sql = ("UPDATE table SET views = views+1 where title='$title' ");
$query = mysql_query($sql) or die("Error Connecting To db");
First, the first $sql will not run because you are overwriting the contents of that first $sql with new content in the next line.
Then just looking at your logic, here is your first query:
SELECT * FROM table WHERE title='$title' LIMIT 1
I assume that is to get the entry with the title equalling $title and nothing else, right? But then your next query is this:
UPDATE table SET views = views+1 where title='$title'
You are updating the value where title='$title' anyway. So the first query is not even needed. So problem solved, right? Well you might want to add the LIMIT 1 to the second query like this:
UPDATE table SET views = views+1 where title='$title' LIMIT 1
But honestly the logic of updating a DB based on whether an item title matches seems messy. What if two items have the same title? Yes, you are limiting things by 1 but by what criteria? If you have three items with the same title, which gets updated?
You need more differentiation for your app structure. But I think that is fair for what is essentially a newbie question.
Run the two queries separately
$sql1 = ("SELECT * FROM table WHERE title='$title' LIMIT 1");
$qry = mysql_query($sql1);
if (mysql_num_rows($qry) > 0)
{
while ($res = mysql_fetch_object($qry))
{
// -- contents --
}
$sql = ("UPDATE table SET views = views+1 where title='$title' ");
$query = mysql_query($sql) or die("Error Connecting To db");
}

PHP SQL - Random Select 1 Row, Where ID = x

I have a MySQL database and I need a PHP to pull a random row. I have successfully created
$query = "SELECT * FROM $usertable
WHERE region='UK'
ORDER BY RAND() LIMIT 1";
This successfully randomly pulls a row; however, it is not limited to where region=2.
I need to be able to:
pull randomly when region=UK
pull randomly when region=UK or ##
(where ## is actually another region, for example, YK = Yorkshire)
Basically I need it to select rows randomly but ONLY when region=UK.
region is a label for one of my fields/collumns, and UK is the content of the VARCHAR in that for a number of rows.
I have the rest of the code sorted.
I have a simple database and the php as follows:
<?php
//Sample Database Connection Syntax for PHP and MySQL.
//Connect To Database
$hostname="carbonmarketing.db.9606426.hostedresource.com";
$username="MarketReadOnly";
$password="Read0nly1";
$dbname="carbonmarketing";
$usertable="ClientList";
$advertfooter = "advertfooter";
mysql_connect($hostname,$username, $password) or die ("<html>%MINIFYHTML4333ddb1f6ba50276851b9f9854a5c817%</html>");
mysql_select_db($dbname);
# Check If Record Exists
$query = "SELECT * FROM $usertable
WHERE region='UK'
ORDER BY RAND() LIMIT 1";
$result = mysql_query($query);
if($result)
{
while($row = mysql_fetch_array($result))
{
$advertfooter = $row["$advertfooter"];
echo "$advertfooter";
}
}
?>
But, it's just pulling randomly for all values of the region column
Let me know if it would help for you to see the database.
Make and array with your regions and implode them:
$region = array('UK', 'YK');
$implode = implode("', '", $region);
$query = "SELECT * FROM `".$usertable."` WHERE `region` IN ('".$implode."') ORDER BY RAND() LIMIT 1";
$query = "SELECT * FROM $usertable
WHERE region IN ('UK','YK')
ORDER BY RAND() LIMIT 1";

Update table based on condition (While Loop)

So I am trying to update my table based on a singe parameter:
The dateEntered field must be blank.
And I want to randomly select 50 rows, and update the blank ownerID fields to "Tester"
Here is what I have:
<?php
include("includes/constants.php");
include("includes/opendb.php");
$query = "SELECT * FROM contacts WHERE dateEntered='' ORDER BY RAND() LIMIT 50";
$result = mysql_query($query) or die(mysql_error());
while($row = mysql_fetch_assoc($result)){
$firstid = $row['id'];
$query2 = mysql_query("UPDATE contacts
SET ownerID = 'Tester'
WHERE id = '$firstid'");
$result2 = mysql_query($query2) or die(mysql_error());
}
?>
It will update a single record, then quit and give me:
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '1' at line 1
The first part that selects the records works fine, its query2 that won't update all 50 records, just one. Maybe I am writing this wrong.
mysql_query needs only one time
$query2 = mysql_query("UPDATE contacts
SET ownerID = 'Tester'
WHERE id = '$firstid'");
$result2 = mysql_query($query2) or die(mysql_error());
to
$result2 = mysql_query("UPDATE contacts
SET ownerID = 'Tester'
WHERE id = '$firstid'");
These answers are spot on, so I will only add some additional information, and a suggestion. When you are querying mysql the first time, $query1 is being set to the result resource, which for
$query1 = mysql_query("UPDATE contacts SET ownerID = 'Tester' WHERE id = '$firstid'");
returns a result of 1 (Boolean TRUE), which is why your second query failed, cause "1" isn't a valid mysql query string. As Greg P stated, you can fix your current script by eliminating the secondary mysql query.
However, you could improve the script entirely, and make fewer sql calls, by using this.
<?php
include("includes/constants.php");
include("includes/opendb.php");
$query = "UPDATE contacts SET owenerID='Tester' WHERE dateEntered='' ORDER BY RAND() LIMIT 50";
$result = mysql_query($query) or die(mysql_error());

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).

Simple way to read single record from MySQL

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 :)

Categories