MYSQL retrieving a field value based on another - php

MYSQL I would like to retrieve a value of a field in columnX where a field value for columnY is specified. There maybe more than one row where this occurs but the first one will do. it would be excellent if you could provide the php. Thanks

Try this SQL:
SELECT `columnX` FROM `table` WHERE `columnY` = $value LIMIT 1
In PHP:
$query = $mysqli->query("SELECT `columnX` FROM `table` WHERE `columnY` = $value LIMIT 1");
$row = $query->fetch_assoc();
echo $row['columnX'];

IF you want to do it in sql you can use the IF condition like :
SELECT IF(X=0,Y,1) As cond FROM table
In PHP:
$query = $mysqli->query('SELECT IF(X=0,Y,1) As cond FROM table');
$row = $query->fetch_assoc();
echo $row['cond'];
thanks to "Daniel Li"

Related

Using a php function in a while loop to get the values and the counts of the values in same column

I am trying to perform a query inside a while loop that is getting values from a column. I am trying to query first to get all my values from a column in my DB and then get the count of how many times that value is in that column.
Examples of output trying to get
myValue is in the column 3 times
myOtherValue is in the column 10 times
myOtherOtherValue is in the column 22 times
Example of code
$sql = "SELECT DISTINCT id, columnName FROM tableName";
$result = mysql_query($sql);
while($row = mysql_fetch_array($result))
{
$id = $row['id'];
function myCount($id)
{
$query = "SELECT COUNT(*) FROM tableName WHERE name = '$id'";
$result = mysql_query($query);
$count = mysql_fetch_array($result);
}
echo "$id is in the column $count[0] times";
}
You can't define a function inside the while loop.
Using COUNT(*) with a GROUP BY name clause, then you could solve the problem with only one query.

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

mysql query written using php

$u_id=$event_assoc['Uniqueid'];
echo $u_id."\n";
$result1 = mysql_query("SELECT * FROM eventdetail WHERE unique_id = '$u_id'", $con1);
while($row = mysql_fetch_array($result1))
{
echo 'in eventdetail'."\n";
$e_id= $row['event_id'];
$destination= $row['destination'];
$uniqueid= $row['unique_id'];
$call_num= $row['channelid'];
}
echo mysql_num_rows($result1);
echo $e_id."\n";
echo $destination."\n";
echo $call_num."\n";
echo $uniqueid."\n";
if(mysql_num_rows($result1)>0)
{
echo 'calculate'."\n";
$result= mysql_query("SELECT sum(billsec)
FROM cdr
WHERE uniqueid = '$uniqueid'", $con2);
$bil = mysql_fetch_array($result);
$bill= (float) $bil['sum(billsec)'];
echo $bill."\n";
this is my code..
whenever i try to execute sum function query it retruns top row's billsec instead of addition of all row's billsec
You are doing a where on an unique ID in the sum query. Remove the where and it'll work
You are using unique id in your query.. And in a table single row will have that id, thats why you are getting top row's billsec... Remove the where clause in second query, and then check.
$result= mysql_query("SELECT sum(billsec)
FROM cdr
WHERE uniqueid = '$uniqueid'", $con2);
i guess there is a bug in this area...look again
The PHP statement for the SQL SUM Query should be:-
$result= mysql_query("SELECT sum(`billsec`), `uniqueid` FROM `cdr` GROUP BY `uniqueid` HAVING `uniqueid` = '$uniqueid'", $con2);
You need to use the clause "GROUP BY" whenever you are using any MySQL Aggregate functions (if needed). Also if you are using any aggregate functions (like "SUM", "MAX" etc), then you cannot use "WHERE" clause on the field (in this case, the field is "uniqueid") which is being used in the "GROUP BY" clause.
Hope it helps.

I am having problem in "fetching" only one entry from mysql

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];

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 :)

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