Access values with PHP from second table after INNER JOIN

Question

I'm trying to join two tables on their id and then populate an empty array with key - values. table2 has an additional city_name column which I'd like to use.

However, after joining the two tables on their id with INNER JOIN, I cannot seem to access the city_name value from the second table (but getting the values from the first table works fine).

Here's my code:

$city_list = array();
$i = 0;

$q = "SELECT * FROM table1 INNER JOIN table2 ON table1.id=table2.city_id";
$res = $mysql_query($q);

while($row = mysql_fetch_assoc($res) {
    $city_list[$i]['id'] = $row['id']; // returns the id from table1, which is also identical to the city_id from table2
    $city_list[$i]['population'] = $row['city_population']; // returns the city_population value from table1 
    $city_list[$i]['name'] = $row['city_name']; // returns null, even though the value exists in table2
    $i++;
}

When printing the $city_list , I get the appropriate id and population values, but the name key has a value of null , even though I have city names in table2 .

Answer 1

Just select the columns you really need.

SELECT table1.id, table1.city_population, table2.city_name 
FROM table1 
INNER JOIN table2 ON table1.id=table2.city_id

Answer 2

You could select the column names using an alias so that you can access both as you want. eg, change query to something like:

SELECT *, table2.user_name as table2_user_name 
FROM table1 
INNER JOIN table2 ON table1.id=table2.city_id

Preferably you shouldn't use * if you don't need all the data. It tends to lead to more bugs & more difficult maintenance.