Combine data from two MySQL tables and echo results using PHP - php

Question

I want to combine data from two MySQL tables and echo results using PHP. The first table is called TEST1 and has two fields(name, info1). The second table is called TEST2 and has also two fields(surname, info2). I would like to select name and surname where info1 = info2 and print name and surname in the same row using PHP. The code I have written so far is this but I don't think it's totally correct for both of the tasks I want it to to do.
$sql = "SELECT name, surname FROM TEST1, TEST2 WHERE info1 = info2";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
while($row = $result->fetch_assoc()) {
echo " - Name: " . $row["name"]. " - Surname: " . $row["surname"]. "<br>";
}
} else {
echo "0 results";
}
$conn->close();
?>
So for example lets say that TEST1 has at name, info1 [(John,112233),(Luke,112244), (Ariana,112255)] and TEST2 has at surname, info2 [(Lala,112255), (Zara,112233), (Azon,112267), (Esora,112248)]. So I want it to display when I visit the webpage:
Name: John - Surname: Zara
Name: Ariana - Surname: Lala
or
Name: Ariana - Surname: Lala
Name: John - Surname: Zara
name, surname, info1, info2 are VARCHAR(64). There seem to be similar quetions but they aren't easy to understand especially for PHP and MySQL beginners who can't understand more advanced scripts cause they are specific to the asker's problem. So I tried to do it general in order to help more people and not just me. Could you please help me? Thanks in advance.

Answer 1

First of all the info data, if stored this way is becoming redundant and consuming more space in your database. If you have several names and surnames pointing to different persons, you just may take one particular name and surname or their id's in a different table and store the info corresponding to that person there.
Table1 = {tableOneId, firstName}
Table2 = {tableTwoId, lastName}
Table3 = {tableThreeId, tableOneId, tableTwoId, info}
This way you can store variety name and surname only once at a time and the information for each person redundantly. Now join these tables to get the desired information.
Select * from `table1`
inner join `table3` on `table1`.`tableOneId` = `table3`.`tableOneId`
inner join `table2` on `table3`.`tableTwoId` = `table2`.`tableTwoId`
Now you can select the name and surname the way you are doing from the result set.

Answer 2

I would add "tableOneId" (or whatever you like) as foreign key to second table that equals to the Id of the first - which will make it primary key. And as I understand that's the basic principle of relational databases.
So structure:
Table1 = {Id, firstName, info}
Table2 = {Id, lastName, info, tableOneId}
Assuming that firstName and lastName always refers to one unique person and you needed to divide this information to two different tables for some reason, you can implement this strategy to have unique identifier as Id in one table and tableOneId to second, to select unique data for one person from both tables.
And query could be something like this:
Select * from `table1`, `table2` where `table1`.`Id` = `table2`.`tableOneId`;