I am doing a sql query but it is not returning any data from the tables. I am not sure why, I have changed from INNER to LEFT but no luck. I have revised the query several times but i cant find an issue. Any thoughts of why I am not getting anything displayed?
TABLE STRUCTURE
TABLE CREATE QUERY
PHP
$query = ("SELECT class.class_name, class.class_caption, class.class_credit_hours, class.class_description, faculty_fname, faculty_lname
FROM class
LEFT JOIN section
ON class.id = section.class_id
LEFT JOIN faculty
ON faculty.id = section.faculty_id OR faculty.id = office_hours.faculty_id
LEFT JOIN faculty_titles
ON faculty_titles.faculty_id = faculty.id
LEFT JOIN faculty_education
ON faculty_education.faculty_id = faculty.id
LEFT JOIN major_class_br
ON major_class_br.class_id = class.id
LEFT JOIN major_minor
ON major_class_br.major_minor_id = major_minor.id
LEFT JOIN sched_sect_br
ON sched_sect_br.section_id = section.id
LEFT JOIN schedule
ON schedule.id = sched_sect_br.schedule_id
LEFT JOIN semester
ON semester.id = schedule.semester_id
LEFT JOIN office_hours
ON schedule.id = office_hours.schedule_id AND faculty.id = office_hours.faculty_id
");
//execute query
$result = mysql_query($query);
if ($result){
$totalhours = 0;
while ($row = mysql_fetch_assoc( $result ))
{
print "<b>" . $row['class_name'] . "</b><br>";
print $row['class_caption'] . "<br>";
print $row ['class_credit_hours'] . "hrs. <br>";
print $row ['faculty_lname'] . "hrs. <br>";
print $row ['faculty_fname'] . "hrs. <br>";
print $row['class_description'] . "<br>";
print "------------------------------<br />";
$totalhours += $row['class_credit_hours'];
}
}
print "<p>Total hours for Major: " . $totalhours . ".</p>";
Desired display:
Computer Programming I
CP1000
4
James Doe
This course offers introduction to programming.
UPDATE: The issue was found here but I am not sure why
ON faculty.id = section.faculty_id OR faculty.id = office_hours.faculty_id
Copy the SQL, go to MySQL admin, execute the SQL there and see if it returns any results.
Remove all the JOIN and execute again, you should see at least something
Add the JOIN one by one
Try to identify which JOIN resulted in no rows being returned
Check the left and right hand side of that join and ensure there actually are valid data to join
Alternatively use OUTER JOIN
Related
I'm trying to get data from two tables: users and posts using left join.
$items = '';
$sql = "
SELECT u.id as uid
, u.name as uname
, p.id as pid
, p.date as pdate
, p.title as ptitle
, p.user as puser
FROM users u
LEFT
JOIN posts p
ON u.id = p.user
WHERE u.role = 'mod'
GROUP
BY p.title;";
$stmt = $db->query($sql);
while($row = $stmt->fetch()){
$date = strtotime($row['pdate']);
$date = date("d-m-Y", $date);
$items.= "<div class='itemp' data-id=" . $row['pid'] . " data-user='" . $row['uname'] . "'>" .
"<span class='spandate'>" . $date . "</span>" .
"<span class='spantitle'>" . $row['ptitle'] . "</span>" .
"<span class='spanuser'>" . $row['uname'] . "</span>" .
"</div>\n";
}
echo $items;
Output is ok except first row where I see the date - 1.1.1970 - but there is no any row in posts with that date. Plus - in the same row ptitle is missing.
Also, is there a better way to create this query, avoiding as keyword ?
desired output (single block):
<div class='itemp' data-id=116 data-user='JOHN SMITH'><span class='spandate'>01-12-2017</span><span class='spantitle'>BLUE SKY</span><span class='spanuser'>JOHN SMITH</span></div>
Also, is there a better way to create this query, avoiding as keyword ?
Yes (but not better in my opinion):
SELECT users.id,
users.name,
posts.id,
posts.date,
posts.title,
posts.user
FROM users
LEFT
JOIN posts
ON users.id = posts.user
WHERE users.role = 'mod'
GROUP
BY posts.title;
But as mentioned in the comments you have to modify your while loop in this case to get access to your values. But I think this is not a better way of writing this query cause it makes it harder to read.
Regarding your JOIN problem. this depends on what your result should be (I guess you only want users with posts ). So you should take a look at INNER JOIN instead of LEFT JOIN. You will get only results which also have posts entrys.
Due to the nature of LEFT JOIN all entrys on the left table (in your case users) will be used, even if they don´t have an entry in the posts table.
INNER JOIN will only return results which match results in both tables.
Here is the query I created :
$query = "SELECT address_details.company, address_details.po_box,
address_details.town, letter_details.address_id,
letter_details.attn, letter_details.create_date,
letter_details.ref_no, letter_details.refference,
letter_details.letter_body, letter_details.print_date
FROM letter_details
join address_details ON address_details.id = letter_details.address_id
join signatories ON (letter_details.id = signatories.id)
WHERE letter_details.id='" .$_GET['id'] . "'";
Try using this query.
$query = "SELECT ad.company, ad.po_box,
ad.town, ld.address_id,
ld.attn, ld.create_date,
ld.ref_no, ld.refference,
ld.letter_body, ld.print_date
FROM letter_details ld
left join address_details ad ON (ad.id = ld.address_id)
left join signatories s ON (ld.id = s.id)
WHERE ld.id='" .$_GET['id'] . "'";
First, you should alias for better readibility,
check if you get something in $_GET[id]
echo $_GET[id];
then assign it, (or you may set it as well, if you're using a class)
$fltr = $_GET[id];
And, try to use LEFT JOIN ;
SELECT b.company, b.po_box,
b.town, a.address_id,
a.attn, a.create_date,
a.ref_no, a.refference,
a.letter_body, a.print_date
FROM letter_details AS a LEFT JOIN address_details AS b ON b.id = a.address_id
LEFT JOIN signatories AS c ON (a.id =c.id)
WHERE a.id='$fltr'
I have php/mysql script running which is like this:
$sql = "select a.column1 from table1 a";
$query = mysql_query($sql);
while ($fec = mysql_fetch_assoc($query)) {
$sub1 = "select column1,column2 from subtable1 where id=" . $fec['a.column1'];
$subquery1 = mysql_query($sub1);
while ($subfec1 = mysql_fetch_assoc($subquery1)) {
//all data .....
}
$sub1 = "select column1,column2 from subtable2 where id=" . $fec['a.column1'];
$subquery2 = mysql_query($sub2);
while ($subfec2 = mysql_fetch_assoc($subquery2)) {
//all data .....
}
$sub2 = "select column1,column2 from subtable3 where id=" . $fec['a.column1'];
$subquery3 = mysql_query($sub3);
while ($subfec3 = mysql_fetch_assoc($subquery3)) {
//all data .....
}
}
Now I've many many many records in table1, subtable1, subtable2 and subtable3. And problem is that it takes around 7 hours to display the results. Moreover the CPU Usage is 100%
Please suggest the optimization tips to overcome this issue.
Use a single query to get all records
SELECT
a.column1,
s.column1,
s.column2,
s2.column1,
s2.column2,
s3.column1,
s3.column2
FROM table1 a
LEFT JOIN subtable1 s ON s.id = a.column1
LEFT JOIN subtable2 s2 ON s.id = a.column1
LEFT JOIN subtable3 s3 ON s.id = a.column1
Here
$sql="
SELECT
a.column1 acolumn1,
s.column1 scolumn1,
s.column2 scolumn2,
s2.column1 s2column1,
s2.column2 s2column2,
s3.column1 s3column1,
s3.column2 s3column2
FROM table1 a
LEFT JOIN subtable1 s ON s.id = a.column1
LEFT JOIN subtable2 s2 ON s.id = a.column1
LEFT JOIN subtable3 s3 ON s.id = a.column1";
$query=mysql_query($sql);
while ($fec=mysql_fetch_assoc($query)) {
// display any info here
}
Use aliases for accessing different table columns
I am currently refactoring a legacy application and converting piece by piece over to zend framework 1.12.
I am scratching my head as to how to convert this over to zend db, is there a way that this can be done in one query?
Right now I see that it fetches a list of folders first and then runs an additional query per folder...
Running this as one query will improve performance, right?
$folders_query = DB::Query("select * from contacts_folders order by sort_order, name");
while($folders = DB::FetchArray($folders_query)){
$counts_total = DB::QueryOne("SELECT count(cm.messages_id) AS total
FROM contacts_basics cb, contacts_messages cm
WHERE cb.contacts_id = cm.contacts_id
AND cm.folders_id = '" . $folders['folders_id'] . "'
AND cm.status = '1'
AND cm.mark = '0'");
if ($counts_total >0){
$folders_name = '<strong>' . $folders['name'] . ' (' . $counts_total . ')</strong>';
} else {
$folders_name = $folders['name'];
}
echo '<li><a href="messages.php?fID=' . $folders['folders_id'] . '">';
echo $folders_name;
echo '</a></li>';
}
Yes, you can do both in the same query
SELECT cf.*, count(cm.messages_id) AS total
FROM contacts_folders cf left outer join
contacts_messages cm
on cf.id = cm.folders_id and
cm.status = '1' AND cm.mark = '0' left outer join
contacts_basics cb
on cb.contacts_id = cm.contacts_id
group by cf.folders_id
order by cf.sort_order, cf.name;
This uses a left outer join to be sure that you get all folders, even if there are no messages (which is how the original code works). Because of the left outer join, the conditions need to be moved into on clauses.
It also fetches all the information from the folders as well as the total. If there are no messages, then it should return 0 for that folder.
There was a minor bug in Gordon's answer but I figured it out thanks to him.
I changed
contacts_basics cb left outer join
To:
left outer join contacts_basics cb
The following code works as expected:
public function getMenuCounts(){
$raw = "SELECT cf.*, count(cm.messages_id) AS total
FROM contacts_folders cf left outer join
contacts_messages cm
on cf.folders_id = cm.folders_id and
cm.status = '1' AND cm.mark = '0'
left outer join contacts_basics cb
on cb.contacts_id = cm.contacts_id
group by cf.folders_id
order by cf.sort_order, cf.name;";
$db = Zend_Db_Table::getDefaultAdapter();
$stmt = $db->query($raw);
return $stmt->fetchAll();
}
here is my code i am using to fetch mysql result from 4 different tables
SELECT DISTINCT c.title as CourseTitle, t.title as TopicTitle, l.title as LessonTitle, r.title as ResourceTitle, r.location, r.type, r.duration
FROM j17_lessons l, j17_topics t, j17_courses c, j17_resources r
WHERE
CONCAT(c.title, t.title, l.title, r.title, r.type, r.location) LIKE '%Fatih%'
AND c.id = t.course_id
AND l.topic_id = t.id
AND r.lesson_id = l.id
ORDER BY c.title, t.id, l.id, r.id;
Here is screen shot of my fetch result
http://i40.tinypic.com/2v1w0ib.png
Now what i need is to create a HTML Tables for each 'CourseTitle' in database.
Using SQL statement and PHP Code i can get result for first query but i need a second query to split table foreach 'CourseTitle'
/* connect to the db */
$connection = mysql_connect('localhost','root','123');
mysql_select_db('alhudapk',$connection);
/* show tables */
$result = mysql_query('SELECT DISTINCT c.title as CourseTitle, t.title as TopicTitle, l.title as LessonTitle, r.title as ResourceTitle, r.location, r.type, r.duration
FROM j17_lessons l, j17_topics t, j17_courses c, j17_resources r
WHERE
CONCAT(c.title, t.title, l.title, r.title, r.type, r.location) LIKE '%Taleem%'
AND c.id = t.course_id
AND l.topic_id = t.id
AND r.lesson_id = l.id
ORDER BY c.title, t.id, l.id, r.id',$connection) or die('cannot show tables');
while($tableName = mysql_fetch_row($result)) {
$table = $tableName[0];
echo '<h3>',$table,'</h3>';
$result2 = mysql_query('SELECT '.$table . 'AS' .$table);
if(mysql_num_rows($result2)) {
Please guide me to build a correct and better code
What I would do is put the database results into a big array structure with the data arranged in the same sort of order it should be printed out. This makes maintaining the code a bit easier.
// run the query as you did in the question
$courses = array();
// use mysql_fetch_assoc as it makes the code clearer
while($row = mysql_fetch_assoc($result)) {
$ct = $row['CourseTitle'];
// Found a new Course Title? If so create an array to put the data rows in
if(!isset($courses[$ct]))
$courses[$ct] = array();
// add this row to the end of its course array
$courses[$ct][] = $row;
}
// now print the results out
foreach($courses as $title =>$course) {
echo "<h3>$title</h3>";
echo "<table>";
foreach($course as $line) {
echo "<tr><td>" . $line['TopicTitle'] . "</td><td>"
. $line['LessonTitle'] . "</td></tr>";
echo "</table>";
}
The code above is only printing out the first 2 columns
, but if you can get it to work you should be able to add the rest quite easily.
add:
GROUP BY c.title
to the end of your SQL statement.