Check if value exists In MySQL row - php

Question

I have a php variable: $foo
My MySQL table called data has the following structure:
id var header
1 zj3 http://google.com
I would like to check if $foo is all ready in var row.
If it is I would like to echo header ("http://google.com")
How would you approach this?
Thanks in advance, please ask if any clarification is needed!

Answer 1

Your query should be:
SELECT `header` FROM `data` WHERE `var` = '$foo'
This will return all the headers with a var value of $foo.
$db = mysqli_connect('localhost', 'username', 'password', 'database');
if($query = mysqli_query($db, "SELECT `header` FROM `data` WHERE `var` = '$foo'")){
while($row = mysqli_fetch_assoc($query)){
echo $row['header'];
}
mysqli_free_result($query);
}

Answer 2

first connect to the db
$query = mysql_query("SELECT var, header FROM data WHERE id='1'") or die(mysql_error());
while($row = mysql_fetch_assoc($query)){
if($foo == $row['var']){
echo $row['header'];
}
}
EDIT: changed equality statement based on your edit

Answer 3

It's not difficult at all, If I understand correctly then this should help you.
// Query Variable / Contains you database query information
$results = $query;
// Loop through like so if the results are returned as an array
foreach($results as $result)
{
if(!$result['var'])
echo $result['header'];
}
// Loop through like so if the results are returned as an object
foreach($results as $result)
{
if(!$result->var)
echo $result->header;
}

Answer 4

are you asking if $foo matches any of the fields in data, or if $foo=some_field? Here for if you want $foo==var.
$foo='somevalue';
$query="SELECT id, var, header FROM `data` WHERE var='$foo'";
$result=mysqli_query($query);
if($result->num_rows==0)
$loc= 'http://google.com';//default value for when there is no row that matches $foo
}else{
$row=$result->fetch_assoc(); //more than one row is useless since the first header('Location: x') command sends the browser to a new page and away from your script.
$loc=$row['header'];
}
header ("Location: $loc);
exit;
ETA: since you've edited your question, it appears that you want to echo the header column if your search value matches your var column. The above won't work for that.

Answer 5

You just want to know if $var's value is anywhere in that column (any row(s))?
SELECT COUNT(id) FROM data WHERE var = ?;
The result will be the number of rows for which the field var contains the value of $var.

Answer 6

Here's a template for all the "does it exist" questions.
This is the only thing that actually worked for me so far and is not deprecated.
if ($query = mysqli_query($link, "SELECT header FROM data WHERE var = '$foo'")) {
$header = mysqli_fetch_assoc($query);
if ($header) {
// The variable with value $foo exists.
}
else {
// The variable with value $foo doesn't exist.
}
}
else {
// The query didn't execute for some reason. (Dammit Obama!)
}
WARNING!
Even if the variable DOES NOT EXIST the comparison between $query and mysqli_query() will always return TRUE.
The only way --which happened to me-- for the comparison to return FALSE is because of a syntax error in your query.
I don't know why it worked for the guy who wrote the accepted answer, maybe it's an update or maybe he had a syntax error and was so confident that he didn't check if it could ever be TRUE.
Here's the comment someone made for correcting his syntax:
"Add another ) before the { in the first line"
So, the accepted answer is WRONG!