I'm trying to figure out a MYSQL string and my noob-ness is getting in my way. I'm trying to count the total number of teams per phase.
Tables to consider:
phases
+----+------------+
| id | phase_name |
+----+------------+
| 1 | start |
| 2 | middle |
| 3 | end |
| 4 | finish |
+----+------------+
teams
+----+-----------+----------+
| id | team_name | phase_id |
+----+-----------+----------+
| 1 | team1 | 2 |
| 2 | team2 | 3 |
| 3 | team3 | 3 |
| 4 | team4 | 4 |
| 4 | team5 | 3 |
+----+-----------+----------+
Desired result
+----------+------------+-----------+
| phase_id | phase_name | tot_teams |
+----------+------------+-----------+
| 1 | start | NULL |
| 2 | middle | 1 |
| 3 | end | 3 |
| 4 | finish | 1 |
+----------+------------+-----------+
I've tried:
SELECT
T.phase_id, P.phase_name, COUNT(*) AS tot_teams
FROM
teams T
LEFT JOIN
phases P ON P.id = T.phase_id
GROUP BY
phase_id;
but that only shows the affected phase_id's...and I'm hoping to get ALL phase_id's in a table. I also tried:
SELECT
P.phase_name, T.phase_id, COUNT(*)
FROM
teams T
RIGHT JOIN
phases P on P.`id` = T.`phase_id`
GROUP BY
P.id
but that shows invalid data. (For example, phase_id has a qty of 1 but doesn't show up in the teams table.
Can you point me in the right direction?
Thanks!
The RIGHT JOIN is correct, but you need to use COUNT(T.phase_id) instead of COUNT(*). Otherwise, you're counting the row containing NULL that's generated for the phase with no teams.
Most people prefer to use LEFT JOIN, putting the master table first.
SELECT P.phase_name, P.phase_name, COUNT(T.phase_id)
FROM phase AS P
LEFT JOIN teams AS T ON P.id = T.phase_id
GROUP BY P.id
Related
I have a MySQL 5.6 database with 3 tables:
job_offer
+----+----------+-------------+-----------+
| id | name | position_id | status_id |
+----+----------+-------------+-----------+
| 1 | John | 1 | 4 |
| 2 | Smith | 1 | 4 |
| 3 | Williams | 2 | 2 |
+----+----------+-------------+-----------+
position
+----+----------+
| id | name |
+----+----------+
| 1 | frontend |
| 2 | backend |
+----+----------+
status
+----+-----------+
| id | name |
+----+-----------+
| 1 | contacted |
| 2 | declined |
| 3 | rejected |
| 4 | interview |
+----+-----------+
I would like to build a query that can count all job offers by their position and statuses.
I have this query that performs almost the way I want it:
SELECT
position.name AS position_name,
status.name AS status_name
COUNT(job_offer.id) AS offers
FROM
job_offer
LEFT OUTER JOIN
position
ON job_offer.position_id = position.id
LEFT OUTER JOIN
status
ON job_offer.status_id = status.id
GROUP BY
position_name, status_name
Which gives me this result:
+---------------+-------------+--------+
| position_name | status_name | offers |
+---------------+-------------+--------+
| frontend | interview | 2 |
| backend | declined | 1 |
+---------------+-------------+--------+
The only problem is that I also need to display all existing statuses related to positions regardless of being NULL. So ideally it should look like this:
+---------------+-------------+--------+
| position_name | status_name | offers |
+---------------+-------------+--------+
| frontend | contacted | 0 |
| frontend | declined | 0 |
| frontend | rejected | 0 |
| frontend | interview | 2 |
| backend | contacted | 0 |
| backend | declined | 1 |
| backend | rejected | 0 |
| backend | interview | 0 |
+---------------+-------------+--------+
Is it possible to achieve this with one query? Thanks in advance for any help.
We can use a cross join approach between the position and status table to generate all possible combinations. Then, left join to job_offer and aggregate by position and status to find the counts:
SELECT
p.name AS position_name,
s.name AS status_name,
COUNT(jo.id) AS offers
FROM position p
CROSS JOIN status s
LEFT JOIN job_offer jo
ON jo.position_id = p.id AND
jo.status_id = s.id
GROUP BY
p.name,
s.name
ORDER BY
p.name,
s.name;
Demo
I have 3 tables to join and need some help to make it work, this is my schema:
donations:
+--------------------+------------+
| uid | amount | date |
+---------+----------+------------+
| 1 | 20 | 2013-10-10 |
| 2 | 5 | 2013-10-03 |
| 2 | 50 | 2013-09-25 |
| 2 | 5 | 2013-10-01 |
+---------+----------+------------+
users:
+----+------------+
| id | username |
+----+------------+
| 1 | rob |
| 2 | mike |
+----+------------+
causes:
+--------------------+------------+
| id | uid | cause | <missing cid (cause id)
+---------+----------+------------+
| 1 | 1 | stop war |
| 2 | 2 | love |
| 3 | 2 | hate |
| 4 | 2 | love |
+---------+----------+------------+
Result I want (data cropped for reading purposes)
+---------+-------------+---------+-------------+
| id | username | amount | cause |
+---------+-------------+---------+-------------+
| 1 | rob | 20 | stop war |
| 2 | mike | 5 | love |
+---------+-------------+-----------------------+
etc...
This is my current query, but returns double data:
SELECT i.*, t.cause as tag_name
FROM users i
INNER JOIN donations tti ON (tti.uid = i.id)
INNER JOIN causes t ON (t.uid = tti.uid)
EDIT: fixed sql schema on fiddle
http://sqlfiddle.com/#!2/0e06c/1 schema and data
How I can do this?
It seems your table's model is not right. There should be a relation between the Causes and Donations.
If not when you do your joins you will get duplicated rows.
For instance. Your model could look like this:
Donations
+--------------------+------------+
| uid | amount | date | causeId
+---------+----------+------------+
| 1 | 20 | 2013-10-10 | 1
| 2 | 5 | 2013-10-03 | 2
| 2 | 50 | 2013-09-25 | 3
| 2 | 5 | 2013-10-01 | 2
+---------+----------+------------+
causes:
+----------------------+
| id | cause |
+---------+------------+
| 1 | stop war |
| 2 | love |
| 3 | hate |
+---------+------------+
And the right query then should be this
SELECT i.*, t.cause as tag_name
FROM users i
INNER JOIN donations tti ON (tti.uid = i.id)
INNER JOIN causes t ON (t.id = tti.causeId)
Try this
SELECT CONCAT(i.username ,' ',i.first_name) `name`,
SUM(tti.amount),
t.cause AS tag_name
FROM users i
LEFT JOIN donations tti ON (tti.uid = i.id)
INNER JOIN causes t ON (t.uid = tti.uid)
GROUP BY i.id
Fiddle
You need to match the id from both the users and causes table at the same time, like so:
SELECT i.*, t.cause as tag_name
FROM users i
INNER JOIN donations tti ON (tti.uid = i.id)
INNER JOIN causes t ON (t.uid = tti.uid and t.id = i.id)
Apologies for formatting, I'm typing this on a phone.
I'm trying to get the top 3 interests of each user, probably as a LEFT JOIN query.
The way the app is designed, each user has a set of interests which are no other than 'childs' (rows without parent) of the categories table.
Here are some simplified table schemas w/mock data (see SQL Fiddle demo)
-- Users table
| ID | NAME |
--------------
| 1 | John |
| 2 | Mary |
| 3 | Chris |
-- Categories table -- Interests table
| ID | NAME | PARENT | | ID | USER_ID | CATEGORY_ID |
-------------------------------------- ------------------------------
| 1 | Web Development | (null) | | 1 | 1 | 1 |
| 2 | Mobile Apps | (null) | | 2 | 1 | 1 |
| 3 | Software Development | (null) | | 3 | 1 | 1 |
| 4 | Marketing & Sales | (null) | | 4 | 2 | 1 |
| 5 | Web Apps | 1 | | 5 | 2 | 1 |
| 6 | CSS | 1 | | 6 | 3 | 1 |
| 7 | iOS | 2 | | 7 | 3 | 1 |
| 8 | Streaming Media | 3 | | 8 | 3 | 1 |
| 9 | SEO | 4 |
| 10 | SEM | 4 |
To get the top 3 interests of a given user, I've usually performed this query:
SELECT `c`.`parent` as `category_id`
FROM `interests` `i` LEFT JOIN `categories` `c` ON `c`.`id` = `i`.`category_id`
WHERE `i`.`user_id` = '2'
GROUP BY `c`.`parent`
ORDER BY count(`c`.`parent`) DESC LIMIT 3
This query returns the top 3 categories (parents) of user with id = 2
I would like to find out how I can query the users table and get their top 3 categories either in 3 different fields (preferred) or as a group_concat(..) in one field
SELECT id, name, top_categories FROM users, (...) WHERE id IN ('1', '2', '3');
Any ideas how I should go about doing this?
Thanks!
First build a groped query that lists on distinct rows, the top three skills for each user. Then pivot that into to pull the three skills for eah user out to the right. You will need to use the Max(isnull(skill,'')) expression on the skills in each skill column.
It is very crude way of doing it in MYSQL to get top 3 records for each user
SELECT u.id, c.name
FROM
users u,
categories c,
(SELECT i.id,
i.user_id,
i.category_id,
#running:=if(#previous=i.user_id,#running,0) + 1 as rId,
#previous:=i.user_id
FROM
(SELECT * FROM intersect ORDER BY user_id) i JOIN
(SELECT #running=0, #previous=0 ) r) i
WHERE
u.id = i.USER_ID AND
i.CATEGORY_ID = c.id AND
i.rId <= 3
group by u.id, c.name ;
Hope it helps
FIDDLE
ticket
+----------+--------+
| ticketID | assign |
+----------+--------+
| 1015 | NULL |
| 1020 | James |
| 1021 | Nick |
+----------+--------+
staffinfo
+---------+-------+
| staffID | staff |
+---------+-------+
| 1 | Jane |
| 2 | James |
| 3 | Nick |
| 4 | Cole |
+---------+-------+
SELECT staff,COUNT(*) as count FROM staffinfo,ticket
WHERE ticket.assign = staffinfo.staff
GROUP BY staff
result:
+-------+-------+
| staff | count |
+-------+-------+
| James | 1 |
| Nick | 1 |
+-------+-------+
Works fine, but infact i need smthing like:
+-------+-------+
| staff | count |
+-------+-------+
| James | 1 |
| Nick | 1 |
| Jane | 0 |
| Cole | 0 |
+-------+-------+
COUNT doesnt count records that arent in the table, and since i just started learning SQL, i wanna ask if theres a way to count as the above result?
you should be using LEFT JOIN
SELECT a.staff, COUNT(b.assign) as count
FROM staffinfo a
LEFT JOIN ticket b
ON b.assign = a.staff
GROUP BY a.staff
SQLFiddle Demo
To fully gain knowledge about joins, kindly visit the link below:
Visual Representation of SQL Joins
Use LEFT JOIN
The LEFT JOIN keyword returns all rows from the left table (table_name1), even if there are no matches in the right table (table_name2).
SELECT staffinfo.staff, count(ticket.assign)
FROM staffinfo
LEFT JOIN ticket
ON ticket.assign =staffinfo.staff
GROUP BY staffinfo.staff
The LEFT JOIN keyword returns all the rows from the left table (staffinfo), even if there are no matches in the right table (ticket).
What I did was, I wanted each user to have their own "unique" numbering system. Instead of auto incrementing the item number by 1, I did it so that Bob's first item would start at #1 and Alice's number would also start at #1. The same goes for rooms and categories. I achieved this by creating "mapping" tables for items, rooms and categories.
The query below works, but I know it can definitely be refactored. I have primary keys in each table (on the "ids").
SELECT unique_item_id as item_id, item_name, category_name, item_value, room_name
FROM
users_items, users_map_item, users_room, users_map_room, users_category, users_map_category
WHERE
users_items.id = users_map_item.map_item_id AND
item_location = users_map_room.unique_room_id AND
users_map_room.map_room_id = users_room.room_id AND
users_map_room.map_user_id = 1 AND
item_category = users_map_category.unique_category_id AND
users_map_category.map_category_id = users_category.category_id AND
users_category.user_id = users_map_category.map_user_id AND
users_map_category.map_user_id = 1
ORDER BY item_name
users_items
| id | item_name | item_location |item_category |
--------------------------------------------------------
| 1 | item_a | 1 | 1 |
| 2 | item_b | 2 | 1 |
| 3 | item_c | 1 | 1 |
users_map_item
| map_item_id | map_user_id | unique_item_id |
----------------------------------------------------
| 1 | 1 | 1 |
| 2 | 1 | 2 |
| 3 | 2 | 1 |
users_rooms
| id | room_name |
----------------------
| 1 | basement |
| 2 | kitchen |
| 3 | attic |
users_map_room
| map_room_id | map_user_id | unique_room_id |
----------------------------------------------------
| 1 | 1 | 1 |
| 2 | 1 | 2 |
| 3 | 2 | 1 |
users_category
| id | room_name |
----------------------
| 1 | antiques |
| 2 | appliance |
| 3 | sporting goods |
users_map_category
| map_room_id | map_user_id | unique_category_id |
----------------------------------------------------
| 1 | 1 | 1 |
| 2 | 1 | 2 |
| 3 | 2 | 1 |
Rewriting your query with explicit JOIN conditions makes it more readable (while doing the same).
SELECT mi.unique_item_id AS item_id
, i.item_name
, c.category_name
, i.item_value
, r.room_name
FROM users_map_item mi
JOIN users_items i ON i.id = mi.map_item_id
JOIN users_map_room mr ON mr.unique_room_id = i.item_location
JOIN users_room r ON r.room_id = mr.map_room_id
JOIN users_map_category mc ON mc.unique_category_id = i.item_category
JOIN users_category c ON (c.user_id, c.category_id)
= (mc.map_user_id, mc.map_category_id)
WHERE mr.map_user_id = 1
AND mc.map_user_id = 1
ORDER BY i.item_name
The result is unchanged. Query plan should be the same. I see no way to improve the query further.
You should use LEFT [OUTER] JOIN instead of [INNER] JOIN if you want to keep rows in the result where no matching rows are found in the right hand table. You may want to move the additional WHERE clauses to the JOIN condition in this case, as it changes the outcome.