missing column data when retrieving rows from a JOIN query - php

Question

In php and mysql I use a join query on several tables. Each table has the field name title. I want to get the value of title from each JOINed table, but when I retrieve each row of my result set with php, I only get the last value of title, This is my query.
SELECT UC.user_id,
UC.courses_id,
UC.semester_id,
UC.batch_id,
UC.department_id,
U.title,
U.firstname,
U.lastname,
B.title ,
CO.title,
SE.title,
DEP.title
FROM tbl_user_courses AS UC
INNER JOIN tbl_user AS U ON UC.user_id = U.id
INNER JOIN tbl_batch AS B ON UC.user_id = B.id
INNER JOIN tbl_courses AS CO ON UC.user_id = CO.id
INNER JOIN tbl_semester AS SE ON UC.user_id = SE.id
INNER JOIN tbl_departments AS DEP ON UC.user_id = DEP.id
where UC.trash=0
order by UC.user_id desc
Its php code
<?php
if($rec)
foreach( $rec as $value => $k){
?>
<?php echo $k['title'];
<?php echo $k['title'];?>
<?php echo $k['title'];?>
<?php echo $k['title'];?>
}
Now How can i get each table title its a field name.

Answer 1

You can give the fields an alias, by adding AS <alias> after the field.
SELECT UC.user_id,
UC.courses_id,
UC.semester_id,
UC.batch_id,
UC.department_id,
U.title as user_title,
U.firstname,
U.lastname,
B.title AS batch_title,
CO.title AS course_title,
SE.title AS semester_title,
DEP.title AS department_title
FROM tbl_user_courses AS UC
INNER JOIN tbl_user AS U ON UC.user_id = U.id
INNER JOIN tbl_batch AS B ON UC.user_id = B.id
INNER JOIN tbl_courses AS CO ON UC.user_id = CO.id
INNER JOIN tbl_semester AS SE ON UC.user_id = SE.id
INNER JOIN tbl_departments AS DEP ON UC.user_id = DEP.id
where UC.trash=0
order by UC.user_id desc
If you run this query, you can use the aliases instead of the field name, so use $k['department_title'] to get the name of the department.
I think that 'title' is a rather odd term to use for the name of department or course, but if they would all be named 'name' you would have the same issue again. :D
By the way, you could use a naming convention to reduce collisions like this. Just like you have department_id (and not just id) you could also use department_name or just department. Still, it's good to know about aliases, because you will need them sooner or later.

Answer 2

When you use fetch_assoc() functions in PHP to retrieve rows from your result set, if some of your columns have the same name you'll lose data. You have, as you know, a whole bunch of columns called title.
You want something like this, putting aliases on some of your result set columns so they don't all have the same name.
These aliases don't change the names of columns in your tables. They change the names of the columns in the results of your query only. When you say
SELECT title AS user_title
it fetches the column named title from the table, but then gives it the name user_title in the result set.
Try this:
SELECT UC.user_id, UC.courses_id, UC.semester_id, UC.batch_id, UC.department_id,
U.title AS user_title,
U.firstname, U.lastname,
B.title AS batch_title,
CO.title AS course_title,
SE.title AS semester_title,
DEP.title AS department_title
...
Then, in php, use code like this....
<?php echo $k['user_title'];
<?php echo $k['batch_title'];?>
<?php echo $k['course_title'];?>
<?php echo $k['semester_title'];?>
<?php echo $k['department_title'];?>
Alternatively, you can, if you're using PDO, fetch each row of your result set into a numbered rather than associative array.
$sth = $dbh->prepare("/*YOUR ORIGINAL QUERY8?") || die "prepare failed";
$sth->execute() || die "execute failed";
while ( $k = $sth->fetch( PDO::FETCH_NUM ) ) {
<?php echo 'batch title: ';echo $k[8];?>
<?php echo 'course title: ';echo $k[9];?>
/* etcetera */
}
This works because it fetches the columns of each row in your result set into a numerically indexed array ( 0 .. n) rather than an associative array.
You can also, in the obsolete mysql API, get the same effect with
while ($k = mysql_fetch_array($resultset, MYSQL_NUM) ) {
/* handle the row */
}