PHP: Running if and else if inside a while loop? - php

Question

I'm trying to run if and else if inside a while loop in my PHP code.
The code looks like this:
<?php
$sql = "SELECT * FROM table ORDER BY id";
$query = mysqli_query($db_conx, $sql);
$productCount = mysqli_num_rows($query);
if ($productCount > 0) {
while($row = mysqli_fetch_array($query, MYSQLI_ASSOC)){
$deviceType = $row["deviceType"];
if($deviceType == 'iPhone' || $deviceType == 'iPad'){
echo 'IOS';
}else if($deviceType == 'Android'){
echo 'Android';
}
}
} else {
}
?>
The code above works (sort of) but not as I was expecting it.
To give you an example, lets say I have 2 rows in MYSQL database.
like this:
id deviceType
1 Android
2 iPhone
when i run my PHP code above, I get this echo-ed on my page:
IOS
IOS
Android
Android
BUT I only have 2 rows in the database so the result should be:
IOS
Android
Could someone please advise on this issue?

Answer 1

This question is clearly misrepresenting your actual code/data.
When your database table has 2 rows, but you are receiving 4 rows then the onus is not on the fetching function, but on your query or database table data.
If your actual query is as posted in your question, then your table data contains more than two rows.
If your actual query is different from what you posted (say, joining the table with a copy of itself), then your data is fine and your query is failing you.
Regardless of if you are using mysqli_fetch_array($result), mysqli_fetch_array($result,MYSQLI_ASSOC), or mysqli_fetch_assoc($result), your while() loop will only do one iteration for each row of data.
The difference in resultset fetching functions:
mysqli_fetch_array($result):
array(0=>'1', 'id'=>'1', 1=>'Android', 'deviceType'=>'Android') // 1 row w/ 4 elements
array(0=>'2', 'id'=>'2', 1=>'iPhone', 'deviceType'=>'iPhone') // 1 row w/ 4 elements
mysqli_fetch_array($result,MYSQLI_ASSOC), or mysqli_fetch_assoc($result):
array('id'=>'1', 'deviceType'=>'Android') // 1 row w/ 2 elements
array('id'=>'2', 'deviceType'=>'iPhone') // 1 row w/ 2 elements
I will rewrite your code and implement some good practices:
if($result=mysqli_query($db_conx,"SELECT `deviceType` FROM `table` ORDER BY `id`;")){
if(mysqli_num_rows($result)){
while($row=mysqli_fetch_assoc($result)){
echo ($row["deviceType"]=="Android"?"Android":"IOS"); // inline condition is a personal preference
}
}else{
echo "No rows in `table`.";
}
}
Only bother declaring a variable if you will use its value more than once (*or if it dramatically improves readability to separate it from its single use.)
So that your variable names are intuitive, name your query variable $sql or $query; and name your query's result variable $result.
Only SELECT columns that you intend to use; * is unnecessary for your case.
Backtick ` wrapping is not required on column and table names, but doing so will avoid any potential clashes with MySQL keywords.
Perform a conditional check and declare the $result variable as false or [resultset] in a single step.
Always check that $result is true before calling any functions that access the resultset. (e.g. mysqli_num_rows() and mysqli_fetch_assoc()).
if(mysqli_num_rows($result)){ will check for a non-falsey value -- I mean 0 equates to false and anything greater than 0 will be true.

Answer 2

Your code appears to be perfectly fine. However, instead of the expected output, you get more items than needed. If I am not mistaken, this means that you have duplicate deviceType in your database table. $productCount probably has a value of 4. You can get two values if you use this query instead:
SELECT DISTINCT `deviceType` FROM `table` ORDER BY `id`
but while this should fix the output you get, your data will still hold duplicates, so you might want to look into the data of your table and into the way it was created, find out and fix the problem.

Answer 3

the answer is very simple you are fetching the results twice with the while loop change this line
while($row = mysqli_fetch_array($query, MYSQLI_ASSOC)){
to
while($row = mysqli_fetch_assoc($query)){
then it will work right, you can see buy the order iPhone iPhone android android that is doing it twice instead of once per loop