Combining two queries and using HAVING - mysql

My solution about this problem is by using 2 queries, but I am wondering if I can do it in one query only.
I have tables like these:
saved_docs
id | user_id | doc_id | date
-----------------------------------------------
1 | 2 | 1 | date
2 | 3 | 2 | date
3 | 2 | 3 | date
docs_list
id | url | title | date
-----------------------------------------
1 | url | title | date
2 | url | title | date
3 | url | title | date
What I want is first to get the doc_id on where the user_id is equal to user's id. Then, get the docs on where the id in the docs_list is equal to doc_id/s I get in saved_docs and order by the saved_docs' date.
This can be done on 2 queries, but if there is a possibility that I can do it in one only then I will go for it.
Here is my current mysql query:
SELECT docs_list.url, docs_list.title
FROM docs_list
INNER JOIN saved_docs
ON saved_posts.user_id = {$user_id}
ORDER BY saved_docs.date DESC
Note: I read about HAVING, problem is I do not know how to apply it to this query.
Current problem:
It is giving me all the docs in which is obvious because it does not give the right doc_id/s (automated). What do I need to do to make this the way I wanted to?
[SOLVED]
Note: Both etsa's and adam's answer solved my problem.

You can try this:
SELECT docs_list.url, docs_list.title
FROM docs_list
INNER JOIN saved_docs ON docs_list.id = saved_docs.doc_id
WHERE saved_posts.user_id = {$user_id}
ORDER BY saved_docs.date DESC

Sounds like you want to do it in the opposite order.
First find all docs saved by user {$user_id}, then fetch the info about those docs and sort the list.
SELECT docs_list.url, docs_list.title
FROM saved_docs
LEFT JOIN docs_list
ON docs_list.id = saved_docs.doc_id
WHERE saved_docs.user_id = {$user_id}
ORDER BY saved_docs.date DESC

Related

Using nested SELECT result for IN statement of another nested SELECT

Be gentle. I'm a high school principal coding on the side for our school site.
I have looked at answers, here, here, and here. I might just not know enough to ask the right question.
We have events that have multiple sessions and there are workshops that can be associated with multiple sessions in multiple events.
I'm trying to get a csv result, later to be put into an array, for the associated sessions and events for my Workshops.
The query below works without the second nested Select statement.
In the Alt_Events statement, I need to pull the Event_IDs that are associated with the Session_IDs that are pulled from the first nested Select.
Events
ID | Name | Description
1 | Flex Learning | A day of flexible learning.
2 | Moonshot Expo | A day to join partners to solve problems.
Event_Sessions
ID | Event_ID | Name | Description
1 | 1 | Morning Session | The first session of the day.
2 | 1 | Afternoon Session | The afternoon session.
3 | 1 | Tutoring Session | A chance to get help from teachers.
4 | 2 | Partner Field Trip | The first session of the day.
5 | 2 | Brainstorming Session | The afternoon session.
6 | 2 | Tutoring Session | A chance to get help from teachers.
Event_Workshops
ID | Name | Description
1 | Math Tutorial | Get help from your math teachers.
Event_Workshop_Links
ID | Workshop_ID | Session_ID
1 | 1 | 3
2 | 1 | 6
Output Table:
ID | Name | Description | ... | Alt_Sessions | Alt_Events
1 | Math Tutorial | Get help... | ... | 3,6 | 1,2
Here is my query.
SELECT
ws.ID, ws.Name, ws.Description, ws.Location, ws.Owner_ID, ws.Max_Attendees,
ws.Eng_Major_Allowed, ws.Eng_Minor_Allowed,
ws.HC_Major_Allowed, ws.HC_Minor_Allowed,
ws.IT_Major_Allowed, ws.IT_Minor_Allowed,
u.LastName as Owner_LastName, u.FirstName AS Owner_FirstName, u.Email AS Owner_Email,
(SELECT group_concat(SESSION_ID) FROM Events_Workshops_Links WHERE Workshop_ID = ws.ID) AS Alt_Sessions,
(SELECT group_concat(Event_ID) FROM Event_Sessions WHERE Session_ID IN Alt_Sessions) AS Alt_Events
FROM Event_Workshops as ws
LEFT JOIN users AS u
ON ws.Owner_ID = u.ID
WHERE ws.ID = ?
ORDER BY ws.Name
I need to be able to pull the all event_ids that are in the Alt_Sessions result.
I'm guessing I can't use the result of the first nested query in the second nested query. If that's the problem, how can I pull that list of event ids?
Any and all help is greatly appreciated.
(Updated to show expected output. Also one error in transcribing the query. Session_ID instead of Event_ID in second nested statement.
Use the subquery instead of Alt_Sessions in the IN predicate like below.
(SELECT group_concat(SESSION_ID) FROM Events_Workshops_Links WHERE Workshop_ID = ws.ID) AS Alt_Sessions,
(SELECT group_concat(Event_ID) FROM Event_Sessions WHERE Session_ID IN (SELECT SESSION_ID FROM Events_Workshops_Links WHERE Workshop_ID = ws.ID)) AS Alt_Events
Also, there is a way to make combinations of Alt_Sessions and Alt_Events first and then join to Event_Workshops.
SELECT * FROM Event_Workshops ws
JOIN
(
SELECT
wsl.Workshop_ID,
GROUP_CONCAT(wsl.Session_ID) Alt_Sessions,
GROUP_CONCAT(wsl.ID) Alt_Events
FROM Event_Workshop_Links wsl
GROUP BY wsl.Workshop_ID
) w
ON ws.ID = w.Workshop_ID

How to select both sum value of all rows and values in some specific rows?

I have a record table and its comment table, like:
| commentId | relatedRecordId | isRead |
|-----------+-----------------+--------|
| 1 | 1 | TRUE |
| 2 | 1 | FALSE |
| 3 | 1 | FALSE |
Now I want to select newCommentCount and allCommentCount as a server response to the browser. Is there any way to select these two fields in one SQL?
I've tried this:
SELECT `isRead`, count(*) AS cnt FROM comment WHERE relatedRecordId=1 GROUP BY `isRead`
| isRead | cnt |
| FALSE | 2 |
| TRUE | 1 |
But, I have to use a special data structure to map it and sum the cnt fields in two rows to get allCommentCount by using an upper-layer programming language. I want to know if I could get the following format of data by SQL only and in one step:
| newCommentCount | allCommentCount |
|-----------------+-----------------|
| 2 | 3 |
I don't even know how to describe the question. So I got no any search result in Google and Stackoverflow. (Because of My poor English, maybe)
Use conditional aggregation:
SELECT SUM(NOT isRead) AS newCommentCount, COUNT(*) AS allCommentCount
FROM comment
WHERE relatedRecordId = 1;
if I under stand you want show sum of newComments Count and all comments so you can do it like
SELECT SUM ( CASE WHEN isRead=false THEN 1 ELSE 0 END ) AS newComment,
Count(*) AS AllComments From comments where relatedRecord=1
also you can make store procedure for it.
To place two result sets horizontally, you can as simple as use a subquery for an expression in the SELECT CLAUSE as long as the number of rows from the result sets match:
select (select count(*) from c_table where isread=false and relatedRecordId=1 ) as newCommentCount,
count(*) as allCommentCount
from c_table where relatedRecordId=1;

MYSQL : Group by all weeks of a year with 0 included

I have a question about some mysql code.
I have a table referencing some employees with the date of arrival et the project id. I wanna calculate all the entries in the enterprise and group it by week.
A this moment, I can have this result
Project ID | Week | Count
1 | 2019-S01 | 2
1 | 2019-S03 | 1
2 | 2019-S01 | 1
2 | 2019-S04 | 5
2 | 2019-S05 | 3
2 | 2019-S06 | 2
This is good, but I would like to have all the weeks returned, even if a week has 0 as result :
Project ID | Week | Count
1 | 2019-S01 | 2
1 | 2019-S02 | 0
1 | 2019-S03 | 1
...
2 | 2019-S01 | 1
2 | 2019-S02 | 0
2 | 2019-S03 | 0
2 | 2019-S04 | 5
2 | 2019-S05 | 3
2 | 2019-S06 | 2
...
Here is my actual code :
SELECT
AP.SECTION_ANALYTIQUE AS SECTION,
FS_GET_FORMAT_SEMAINE(AP.DATE_ARRIVEE_PROJET) AS SEMAINE,
Count(*) AS COMPTE
FROM
RT00_AFFECTATIONS_PREV AP
WHERE
(AP.DATE_ARRIVEE_PROJET <= CURDATE() AND Year(AP.DATE_ARRIVEE_PROJET) >= Year(CURDATE()))
GROUP BY
SECTION, SEMAINE
ORDER BY
SECTION
Does anybody have a solution ?
I searched things on internet but didn't find anything accurate :(
Thank you in advance ! :)
The classic way to meet this requirement is to create a referential table to store all possible weeks.
create table all_weeks(week varchar(8) primary key);
insert into all_weeks values
('2019-S01'), ('2019-S02'), ('2019-S03'), ('2019-S04'), ('2019-S05'), ('2019-S06');
Once this is done, you can generate a cartesian product of all possible sections and weeks with a CROSS JOIN, and LEFT JOIN that with the original table.
Given your code snippet, this should look like:
SELECT
s.section_analytique AS section,
w.week AS semaine,
COUNT(ap.section_analytique) AS compte
FROM
(SELECT DISTINCT section_analytique from rt00_affectations_prev) s
CROSS JOIN all_weeks w
LEFT JOIN rt00_affectations_prev ap
ON s.section_analytique = ap.section_analytique AND w.week = FS_GET_FORMAT_SEMAINE(ap.date_arrivee_projet)
GROUP BY s.section_analytique, w.week
ORDER BY s.section_analytique
PS: be careful not to put conditions on the original table in the WHERE clause: this would defeat the purpose of the LEFT JOIN. If you need to do some filtering, use the referential table instead (you might need to add a few columns to it, like the starting date of the week maybe).

Select count with value from different tables

I want to count all entries in one table grouped by the user id.
This is the query I used which works fine.
select uuid_mapping_id, count(*) from t_message group by uuid_mapping_id;
and these are the results:
+-----------------+----------+
| uuid_mapping_id | count(*) |
+-----------------+----------+
| 1 | 65 |
| 4 | 277 |
Now I would like to display the actual user name, instead of the ID.
To achieve this I would need the help of two different tables.
The table t_uuid_mapping which has two columns:
uid_mapping_id, which equals uuid_mapping_id in the other table.
And f_uuid which is also unique but completely different.
f_uuid can also be found in another table t_abook which also contains the names in the column f_name.
The result I am looking for should be:
+-----------------+----------+
| f_name | count(*) |
+-----------------+----------+
| admin | 65 |
| user1 | 277 |
I am new to the database topic and understand that this could be achieved by using JOIN in the query, but to be honest I did not completely understand this yet.
if I understand you correctly:
SELECT tm.f_name, COUNT(*) as count
FROM t_message tm
LEFT JOIN t_abook ta ON (tm.uuid_mapping_id = ta.uid_mapping_id)
GROUP BY tm.f_name

mysql query - conditional statements?

Here are my tables:
files
+----+--------+
| id | name |
+----+--------+
| 2 | file_1 |
| 3 | file_2 |
| 5 | file_3 |
+----+--------+
files_already_viewed
+----+---------+----------+------+
| id | file_id | category | user |
+----+---------+----------+------+
| 1 | 3 | 5 | 1 |
| 2 | 2 | 1 | 1 |
| 3 | 5 | 1 | 1 |
+----+---------+----------+------+
categories_files_join
+--------+---------+
| cat_id | file_id |
+--------+---------+
| 1 | 2 |
| 1 | 5 |
| 5 | 3 |
| 1 | 3 |
+--------+---------+
file_2 (which has an id of 3) has two categories associated with it, cat_id 5 and cat_id 1.
It has been viewed once by a user searching for files under the category 5.
But now the user is searching for files under the category 1.
I need a query that won't show file_2 under the "1" category until all the other files with a category id of 1 have been viewed first, since the user already viewed file_2. Basically putting file_2 at the end of the list.
Here is my query so far:
SELECT name FROM files
WHERE files.id NOT IN (
SELECT file_id FROM files_already_viewed
WHERE user='1')
ORDER BY most_viewed DESC
LIMIT 1
I order my search by the most popular viewed file. But i don't want to show files that have already been viewed regardless of category until all other files have been viewed with in that specific category.
Any help would be greatly appreciated. thanks!
Actually, your query will not show files already shown. What you want to do is to order those already shown files at the bottom. So, basically you'll have to sets of data: first, the data that matches the needed criteria and that the user has not been shown yet and then the data that matches the needed criteria but the user has been shown.
The way I'm handling the sets is by adding a customSort id for each set and then ordering by it. Now the short explanation is that the first group I get it by faking a MINUS operation with a left join: I get all the files that have not yet been seen. Then, the second group is a bit easier as it just needs to get all the files that have already been seen. So, the UNION of both sets in the customSort order would be the result you're looking for so now you just need to filter that result by the current query criteria (category = 1 in this case).
select file_id from (
select distinct cf1.cat_id, cf1.file_id, 1 as customSort
from CategoriesFiles1 cf1
left join FilesViewed1 fv1 on (fv1.file_id = cf1.file_id)
where (fv1.file_id is null)
union
select distinct cf2.cat_id, cf2.file_id, 2 as customSort
from CategoriesFiles2 cf2
join FilesViewed2 fv2 on (fv2.file_id = cf2.file_id)
) FinalResult
where (FinalResult.cat_id = 1)
order by customSort
Here is a link with the example. You can comment each data insert in files_already_viewed to see how, after viewing a file, the result changes. Besides, changing select file_id from to select * from will allow you to clearly see which set each row belongs to.
Let me know if this works.