Is it okay use the same variable name on PHP while? - php

Question

I just wondering is it okay if I use the following code :
$query = mysqli_query($db, "SELECT * FROM myTable1")
while($result = mysqli_fetch_assoc($query)){
$temp = $result['id'];
}
Then I fetch another table like this :
$query = mysqli_query($db, "SELECT * FROM myTable2")
while($result = mysqli_fetch_assoc($query)){
$temp = $result['id'];
}
I use the same variable $result and $temp.
I mean is it okay to use such code ? Should I named the variable differently like $result1 $result2 and so on ?
Let's say, which one is better, safer, between use the same variable name or give the variables different name ?
I hope someone could explain about it.
Thank you before.

Answer 1

If you follow SOLID principle, especially the single responsibility principle wants you to isolate functionality into different function.
If you do apply this, then you are not really using the same variables, because at that point there would be in different scope, therefore it would not be an issue.
In short you shouldn't have to reuse variables, if your logic is broken up into function that perform a single task, please do not name them $result1, result2 etc ... this is a sign of code smell in your project.

Answer 2

If you are done with myTable1 then it is totally ok but if you are going to use it somewhere else in code then no because only myTable2 information will be saved in $result

Answer 3

if you use same variable to store your data then every iteration the variable value will be override with new value, and the value after while statement is the last iteration.

Answer 4

$temp is a local variable to the while if you haven't defined it before so it is safe to be used like that.
$query, from what the language lets you do, yes you can use it this way.

Answer 5

Basic PHP code
Let's say you want to store some information from database into variable and then use it before doing some more coding.
So we have this sample code. Storing id value into $temp variable. What is the output we get?
$query = mysqli_query($db, "SELECT * FROM myTable1")
while($result = mysqli_fetch_assoc($query)){
$temp = $result['id'];
}
For example table myTable1 contains data like this.
+----+---------+---------+
| id | Col1 | Col2 |
+----+---------+---------+
| 1 | Value 1 | Value 2 |
| 2 | Value 1 | Value 2 |
| 3 | Value 1 | Value 2 |
| 4 | Value 1 | Value 2 |
+----+---------+---------+
Our $temp variable will be equal to 4. Because you are getting everything from that table and then fetching every result that comes up. Now, let's use that variable.
echo 'Selected id from table myTable1 equals ' . $temp;
Which results in
Selected id from table myTable1 equals 4
Then, we are getting data from another table called myTable2.
$query = mysqli_query($db, "SELECT * FROM myTable2")
while($result = mysqli_fetch_assoc($query)){
$temp = $result['id'];
}
That table contains data like this.
+----+---------+---------+
| id | Col1 | Col2 |
+----+---------+---------+
| 3 | Value 1 | Value 2 |
| 5 | Value 1 | Value 2 |
| 6 | Value 1 | Value 2 |
| 8 | Value 1 | Value 2 |
+----+---------+---------+
Again, same thing happens, $temp variable is now equal to 8. Let's use it same way.
echo 'Selected id from table myTable2 equals ' . $temp;
Which results in
Selected id from table myTable2 equals 8
Final result
Selected id from table myTable1 equals 4
Selected id from table myTable2 equals 8
Conclusion
Nothing wrong here. You can do that if you want. But be aware that it's not recommended to use variable with same name multiple times if you have way more lines of code.
More complex PHP code
Same tables, structure and data. Let's change code.
function printIndex($id) {
echo 'Index = ' . $id;
}
$query = mysqli_query($db, "SELECT * FROM myTable1")
while($result = mysqli_fetch_assoc($query)){
$temp = $result['id']; // Store id for further use
}
$query = mysqli_query($db, "SELECT * FROM myTable2")
while($result = mysqli_fetch_assoc($query)){
$temp = $result['id']; // Store id for further use
}
printIndex($temp); // Print stored id
Output
Index = 8
Conclusion
Bad coding. You have to use unique variable names to prevent such situation.

Answer 6

You can use the same variable names logically. It won't give you an error(sometimes it might if you use these variables out of your loop in this context). But using general keywords for variable names are not advisable.
Instead try to name the variables based on your Model. Please look at the below examples,
If your 'myTable1' about students then you can use $student instead of $result1.
Again, if your 'myTable2' is about products then you can use $product instead of $result2.