MySQL - Query a temp table to retrieve 2 rows from table - php

Thank you for taking the time to read my question.
I am trying to combine data from 2 tables in such a way that it can be presented on a webpage with PHP -- I am using a WordPress site so the table structure may look familiar.
The table layout:
wp_3bpf9a_posts - This table has 1 row for each 'post', and I need this table so I can query for a specific type of post, and also obtain the date.
wp_3bpf9a_postmeta - Table with many records for each post (there is an ID that links the two together). I actually need data from 2 (of many) rows for each ID to complete the displayed dataset I am looking for.
I tried to accomplish this by creating a temp table joining the first record together between both tables, and then I was going to go back and join the temp table to the second record I needed. I actually connected to MySQL DB using Toad, and got the code below to work when I run each statement below one at a time in sequence. When I try to run the whole thing I do not get an error but also get no results, same when I try it on my PHP page. I know there is likely an easier way to do this, but this was my first step out of a simple MySQL query. Any guidance that you could provide would be appreciated, thanks!
DROP TABLE IF EXISTS bookingTempTable;
CREATE TEMPORARY TABLE bookingTempTable AS
SELECT ID, post_title, post_name, meta_value
FROM `wp_3bpf9a_posts`
INNER JOIN `wp_3bpf9a_postmeta` ON `wp_3bpf9a_postmeta`.`post_id`=`wp_3bpf9a_posts`.`ID`
WHERE `post_type` LIKE 'booked_appointments' AND `post_title` LIKE '%October 9%' AND `wp_3bpf9a_postmeta`.`meta_key` LIKE 'slot_members';
SELECT *
FROM `wp_3bpf9a_postmeta`
INNER JOIN `bookingTempTable` ON `bookingTempTable`.`ID`=`wp_3bpf9a_postmeta`.`post_id`
WHERE `wp_3bpf9a_postmeta`.`meta_key` LIKE '_appointment_timeslot'
ORDER by `wp_3bpf9a_postmeta`.`meta_value` ASC;

You don't need the temporary table, just join with wp_sbpf9a_postmeta twice.
SELECT p.*, m1.meta_value AS slot_member, m2.meta_value AS appointment_timeslot
FROM wp_sbpf9a_posts AS p
JOIN wp_3bpf9a_postmeta AS m1 ON p.id = m1.post_id
JOIN wp_sbpf9a_postmeta AS m2 ON p.id = m2.post_id
WHERE p.post_type = 'booked_appointments'
AND p.post_title LIKE '%October 9%'
AND m1.meta_key = 'slot_members'
AND m2.meta_key = '_appointment_timeslot'
ORDER BY appointment_timeslot

Related

Is it possible with MySQL to generate a query to fetch from several tables even if one has no results?

I'm facing a problem here:
I'm building a forum, this forum has several tables and I'm trying to fetch the comments and user info in a single query.
So far, it should be easy, the problem is that I can't change the structure and with the following query I get a perfect result IF there is a like to the answer. If no one likes the answer it fails.
Select
mfr.mfr_forum_answers.id,
mfr.mfr_forum_answers.date_created,
mfr.mfr_forum_answers.last_updated,
mfr.mfr_forum_answers.content,
mfr.mfr_forum_answers.accepted,
mfr.mfr_forum_answers.user_id,
mfr.mfr_users.level,
mfr.mfr_users.avatar,
mfr.mfr_forum_likes.subject_id,
mfr.wp_users.ID As ID1,
mfr.mfr_forum_topics.user_id As owner_id,
(SELECT count(mfr.mfr_forum_likes.id) FROM mfr.mfr_forum_likes WHERE mfr.mfr_forum_likes.subject_id = :id AND mfr.mfr_forum_likes.type = 'answer') as likes,
(SELECT count(mfr.mfr_forum_likes.id) FROM mfr.mfr_forum_likes WHERE mfr.mfr_forum_likes.subject_id = :id AND makefitreal.mfr_forum_likes.type = 'answer' AND mfr.mfr_forum_likes.user_id = :sessionId ) as i_like,
mfr.wp_users.user_nicename
From
mfr.mfr_forum_likes Inner Join
mfr.mfr_forum_answers
On mfr.mfr_forum_answers.topic_id =
mfr.mfr_forum_likes.subject_id Inner Join
mfr.mfr_users
On mfr.mfr_forum_answers.user_id = mfr.mfr_users.id
Inner Join
mfr.wp_users
On mfr.mfr_users.id = mfr.wp_users.ID Inner Join
mfr.mfr_forum_topics
On mfr.mfr_forum_answers.topic_id = mfr.mfr_forum_topics.id
Where
mfr.mfr_forum_answers.topic_id = :id
And
mfr.mfr_forum_likes.type = 'answer'
So far as said it returns only if an answer has a like, I'm thinking on adding a add to the user who posts the answer by default but I'm trying to improve my skills by solving new issues.
If someone has a suggestion in how I could overcome the fact that if a table is empty, the query continues I'd be really thankfull.
Thanks in advance-
Pihh
Yes. What you are looking for are called left and right joins. According to the documentation, with a LEFT JOIN you still join two tables as normal but
If there is no matching row for the right table in the ON or USING part in a LEFT JOIN, a row with all columns set to NULL is used for the right table.
This means that you can try to join two tables, but if a row does not have any results it will still return the results from the first table. The same is true for a RIGHT JOIN only it works the opposite way: it will return results if the tabled being joined to has results, but the original table does not.
It looks like you have 3 tables for 3 relationships: there are answers, a user gives an answer, and an answer might or might not have like. To grab this data, I would suggest starting from your answers table, performing an INNER JOIN on your users table (assuming there are always users), and a LEFT JOIN on your likes table. Here is a simple example:
SELECT *
FROM answers
INNER JOIN users ON users.id = answers.user_id
LEFT JOIN likes ON likes.answer_id = answer.id
WHERE answers.id = :id
AND likes.type = 'answers'
Of course, if for some unknown reason you need to start from your likes table, then you'd have to RIGHT JOIN the other tables. I hope that gives you a good idea of how you'd make your query.

Multi-Table, Multi-WHERE and SELECT MySQL query

So, I am trying to select some data from 4 tables using a query I have attempted to throw together.
SELECT *
FROM cards
LEFT JOIN cards_viewers ON cards.card_id = cards_viewers.card_id
(SELECT *
FROM folders
WHERE folder_id = cards.card_folderID)
(SELECT user_firstName,
user_lastName,
user_avatar
FROM user_data
WHERE user_id = cards_viewers.user_id)
WHERE cards_viewers.user_id = '.$u_id.'
ORDER BY cards.card_lastUpdated DESC
Basically, the query selects data from the four tables depending on the user_id in table user_data. I have attempted to initially fetch all data from the tables cards, and cards_viewers, and have went on to use this data to select values from the other tables (user_data and folders).
The query is wrong, I know that. I have learnt the majority of basic MySQL, but I am still struggling with more complex queries like the one I am trying to write now. What query can I use to select the data I want?
Links to any documentation to parts of queries would prove very useful in helping me learn how to create queries in future, rather than just relying on StackOverflow.
Many thanks.
You don't need "MULTI-WHERE" but multiple joins, you just need to keep doing joins until you get the tables you need.
Here's an example:
SELECT *
FROM cards LEFT JOIN cards_viewers
ON cards.card_id = cards_viewers.card_id
LEFT JOIN folders
ON folders.folder_id = cards.card_folderID
LEFT JOIN user_data
ON user_id = cards_viewers.user_id
WHERE cards_viewers.user_id = '.$u_id.'
ORDER BY cards.card_lastUpdated DESC
To custom the fields you want to get just change * for the name of the field being careful about ambiguous column naming.
For further information check MySql Joins. Hope this helped you :)

Multiple table select grouped query

We need to grab the last and newest 20 entries from different tables. However, the GROUP BY statement skips records because we are working with LEFT JOIN on tables.
All these records are linked to unique persons in another table. We store these person's id's in an array for more queries later.
We have a few tables (in which all those person id's are stored) and we want to get them sorted and grouped.
The tables are like this:
SELECT lastRecord+personID FROM t1
SELECT lastRecord+personID FROM t2
SELECT lastRecord+personID FROM t3
SELECT lastRecord+personID FROM t4
WHERE t5.Essential_Column_Name = '1'
GROUP BY personID
ORDER BY 'all the latest entries'
LIMIT 20
With that, the relevance of all the latest entries should be equal.
We do have a timestamp column as well. Perhaps that might work better.
Any input is highly appreciated!
For people looking for an answer on this; this is the right post, answer and update to this Q:
UNION mysql gives weird numbered results
With thanks to all for the ideas and providing the paths to the right solution.

MySql - Joining another table with multiple rows, inserting a query into a another query?

I've been racking my brain for hours trying work out how to join these two queries..
My goal is to return multiple venue rows (from venues) based on certain criteria... which is what my current query does....
SELECT venues.id AS ven_id,
venues.venue_name,
venues.sub_category_id,
venues.score,
venues.lat,
venues.lng,
venues.short_description,
sub_categories.id,
sub_categories.sub_cat_name,
sub_categories.category_id,
categories.id,
categories.category_name,
((ACOS( SIN(51.44*PI()/180)*SIN(lat*PI()/180) + COS(51.44*PI()/180)*COS(lat*PI()/180)*COS((-2.60796 - lng)*PI()/180)) * 180/PI())*60 * 1.1515) AS dist
FROM venues,
sub_categories,
categories
WHERE
venues.sub_category_id = sub_categories.id
AND sub_categories.category_id = categories.id
HAVING
dist < 5
ORDER BY score DESC
LIMIT 0, 100
However, I need to include another field in this query (thumbnail), which comes from another table (venue_images). The idea is to extract one image row based on which venue it's related to and it's order. Only one image needs to be extracted however. So LIMIT 1.
I basically need to insert this query:
SELECT
venue_images.thumb_image_filename,
venue_images.image_venue_id,
venue_images.image_order
FROM venue_images
WHERE venue_images.image_venue_id = ven_id //id from above query
ORDER BY venue_images.image_order
LIMIT 1
Into my first query, and label this new field as "thumbnail".
Any help would really be appreciated. Thanks!
First of all, you could write the first query using INNER JOIN:
SELECT
...
FROM
venues INNER JOIN sub_categories ON venues.sub_category_id = sub_categories.id
INNER JOIN categories ON sub_categories.category_id = categories.id
HAVING
...
the result should be identical, but i like this one more.
What I'd like to do next is to JOIN a subquery, something like this:
...
INNER JOIN (SELECT ... FROM venue_images
WHERE venue_images.image_venue_id = ven_id //id from above query
ORDER BY venue_images.image_order
LIMIT 1) first_image
but unfortunately this subquery can't see ven_id because it is evaluated first, before the outer query (I think it's a limitation of MySql), so we can't use that and we have to find another solution. And since you are using LIMIT 1, it's not easy to rewrite the condition you need using just JOINS.
It would be easier if MySql provided a FIRST() aggregate function, but since it doesn't, we have to simulate it, see for example this question: How to fetch the first and last record of a grouped record in a MySQL query with aggregate functions?
So using this trick, you can write a query that extracts first image_id for every image_venue_id:
SELECT
image_venue_id,
SUBSTRING_INDEX(
GROUP_CONCAT(image_id order by venue_images.image_order),',',1) as first_image_id
FROM venue_images
GROUP BY image_venue_id
and this query could be integrated in your query above:
SELECT
...
FROM
venues INNER JOIN sub_categories ON venues.sub_category_id = sub_categories.id
INNER JOIN categories ON sub_categories.category_id = categories.id
INNER JOIN (the query above) first_image on first_image.image_venue_id = venues.id
INNER JOIN venue_images on first_image.first_image_id = venue_images.image_id
HAVING
...
I also added one more JOIN, to join the first image id with the actual image. I couldn't check your query but the idea is to procede like this.
Since the query is now becoming more complicated and difficult to mantain, i think it would be better to create a view that extracts the first image for every venue, and then join just the view in your query. This is just an idea. Let me know if it works or if you need any help!
I'm not too sure about your data but a JOIN with the thumbnails table and a group by on your large query would probably work.
GROUP BY venues.id

Mysql join query retrieving profile images of users with ids from other table

I'm having trouble with a join query, my issue is as follows.
Table: battles
Fields: id,attacker_id,defender_id
Table: users
Fields: id,profile_image
I would like to do a query to retrieve a battle and get the profile images as well from the other table.
Is there a way to do this in a single or do I have to do more than one?
Thanks in advance.
I wanted to wait a while to see if you had any attempt or if you will answer my first question to know if I understood the problem. But maybe you don't have a starting point. Try something like:
SELECT
a.profile_image as attacker_profile_image,
d.profile_image as defender_profile_image
FROM
`battles` b
LEFT JOIN
`users` a
ON
b.`attacker_id` = a.`id`
LEFT JOIN
`users` d
ON
b.`defender_id` = d.`id`
the problem here is the fact that you need to join with the users table twice, so you will need to create aliases for the columns you plan to use
This query will fetch the two images only, you will need to add the extra fields

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