I have 3 tables
admin_courses
Admin_course_groups
Group_permision
admin_courses
c_id | c_name | c_status
1 | test1 | 1
2 |test2 |1
3 |test3 |1
4 test4 1
Admin_course_groups
a_id | fk_c_id |fk_g_id |start_date |end_date
1 | 1 | 1 | 2018-10-10 |2018-10-20
2 | 5 |1 | 2018-10-10 | 2018-10-20
3 | 4 |3 |2018-10-10 |2018-10-20
Group_permision
gp_id|fk_g_id|user_id
1 1 2
2 3 2
2 1 3
Here total four courses added i want to know how many course assign to each user, i have query
SELECT c_id
, c_name
, COUNT(a_id) AS nam
, MIN(start_date) as start_date
, MIN(end_date) as end_date
FROM admin_courses c
LEFT
JOIN Admin_course_groups g
ON g.fk_c_id = c.c_id
left
join Group_permision h
on g. fk_g_id=h.fk_g_id
and users_id=3
where c.c_status=1
GROUP
BY c_id
So here it will return all course, if course is assigned for user COUNT(a_id) will 1 else it 0.
Now my issue is that if users_id is 3 user assigned only 1 course but i got 3 instead of 1.
Please help me. any help would be appreciated.
You are counting wrong field. To count number of Users in a Course, you need to count user_id; Also, use Count(Distinct ...) to avoid counting a same user multiple times.
Also, note that I have added c.c_name to Group By clause, to be compatible with only_full_group_by mode. Do Read: SELECT list is not in GROUP BY clause and contains nonaggregated column .... incompatible with sql_mode=only_full_group_by
You dont need to join on user_id, to count total number of users. It restricts your data.
Try:
SELECT c.c_id
, c.c_name
, COUNT(DISTINCT h.user_id) AS nam
, MIN(g.start_date) AS start_date
, MIN(g.end_date) AS end_date
FROM admin_courses AS c
LEFT
JOIN Admin_course_groups AS g
ON g.fk_c_id = c.c_id
LEFT
JOIN Group_permision AS h
on g.fk_g_id = h.fk_g_id
WHERE c.c_status=1
GROUP
BY c.c_id,
c.c_name
Your question is missing some crucial information, but if I understood the problem correctly, I would simply try to add Distinct to the count :
SELECT `c_id`, `c_name`, COUNT(distinct `a_id`)
....
Related
Here's what I'm trying to do. Let's say I have this table t:
key_id | id | record_date | other_cols
1 | 18 | 2011-04-03 | x
2 | 18 | 2012-05-19 | y
3 | 18 | 2012-08-09 | z
4 | 19 | 2009-06-01 | a
5 | 19 | 2011-04-03 | b
6 | 19 | 2011-10-25 | c
7 | 19 | 2012-08-09 | d
For each id, I want to select the row containing the minimum record_date. So I'd get:
key_id | id | record_date | other_cols
1 | 18 | 2011-04-03 | x
4 | 19 | 2009-06-01 | a
The only solutions I've seen to this problem assume that all record_date entries are distinct, but that is not this case in my data. Using a subquery and an inner join with two conditions would give me duplicate rows for some ids, which I don't want:
key_id | id | record_date | other_cols
1 | 18 | 2011-04-03 | x
5 | 19 | 2011-04-03 | b
4 | 19 | 2009-06-01 | a
How about something like:
SELECT mt.*
FROM MyTable mt INNER JOIN
(
SELECT id, MIN(record_date) AS MinDate
FROM MyTable
GROUP BY id
) t ON mt.id = t.id AND mt.record_date = t.MinDate
This gets the minimum date per ID, and then gets the values based on those values. The only time you would have duplicates is if there are duplicate minimum record_dates for the same ID.
I could get to your expected result just by doing this in mysql:
SELECT id, min(record_date), other_cols
FROM mytable
GROUP BY id
Does this work for you?
To get the cheapest product in each category, you use the MIN() function in a correlated subquery as follows:
SELECT categoryid,
productid,
productName,
unitprice
FROM products a WHERE unitprice = (
SELECT MIN(unitprice)
FROM products b
WHERE b.categoryid = a.categoryid)
The outer query scans all rows in the products table and returns the products that have unit prices match with the lowest price in each category returned by the correlated subquery.
I would like to add to some of the other answers here, if you don't need the first item but say the second number for example you can use rownumber in a subquery and base your result set off of that.
SELECT * FROM
(
SELECT
ROW_NUM() OVER (PARTITION BY Id ORDER BY record_date, other_cols) as rownum,
*
FROM products P
) INNER
WHERE rownum = 2
This also allows you to order off multiple columns in the subquery which may help if two record_dates have identical values. You can also partition off of multiple columns if needed by delimiting them with a comma
This does it simply:
select t2.id,t2.record_date,t2.other_cols
from (select ROW_NUMBER() over(partition by id order by record_date)as rownum,id,record_date,other_cols from MyTable)t2
where t2.rownum = 1
If record_date has no duplicates within a group:
think of it as of filtering. Simpliy get (WHERE) one (MIN(record_date)) row from the current group:
SELECT * FROM t t1 WHERE record_date = (
select MIN(record_date)
from t t2 where t2.group_id = t1.group_id)
If there could be 2+ min record_date within a group:
filter out non-min rows (see above)
then (AND) pick only one from the 2+ min record_date rows, within the given group_id. E.g. pick the one with the min unique key:
AND key_id = (select MIN(key_id)
from t t3 where t3.record_date = t1.record_date
and t3.group_id = t1.group_id)
so
key_id | group_id | record_date | other_cols
1 | 18 | 2011-04-03 | x
4 | 19 | 2009-06-01 | a
8 | 19 | 2009-06-01 | e
will select key_ids: #1 and #4
SELECT p.* FROM tbl p
INNER JOIN(
SELECT t.id, MIN(record_date) AS MinDate
FROM tbl t
GROUP BY t.id
) t ON p.id = t.id AND p.record_date = t.MinDate
GROUP BY p.id
This code eliminates duplicate record_date in case there are same ids with same record_date.
If you want duplicates, remove the last line GROUP BY p.id.
This a old question, but this can useful for someone
In my case i can't using a sub query because i have a big query and i need using min() on my result, if i use sub query the db need reexecute my big query. i'm using Mysql
select t.*
from (select m.*, #g := 0
from MyTable m --here i have a big query
order by id, record_date) t
where (1 = case when #g = 0 or #g <> id then 1 else 0 end )
and (#g := id) IS NOT NULL
Basically I ordered the result and then put a variable in order to get only the first record in each group.
The below query takes the first date for each work order (in a table of showing all status changes):
SELECT
WORKORDERNUM,
MIN(DATE)
FROM
WORKORDERS
WHERE
DATE >= to_date('2015-01-01','YYYY-MM-DD')
GROUP BY
WORKORDERNUM
select
department,
min_salary,
(select s1.last_name from staff s1 where s1.salary=s3.min_salary ) lastname
from
(select department, min (salary) min_salary from staff s2 group by s2.department) s3
I have three tables:
person_table
id| name | gender
1 | Joe | male
2 | Jane |female
3 | Janet | female
4| Jay | male
etc...
product_table
id| name
1 | magazine
2 | book
3 |paper
4 | novel
etc...
**person_product
person_id| product_id | quantity
1 | 1 | 1
1 | 3 | 3
2 | 3 | 1
4 | 4 | 2
etc...
I have tried to make a query that will return a table like this:
person_id| person_name | product_name| quantity
but i can't make it so that if lets say John has no books, it should display
(johns id) John|book|0
instead of just skipping this line.
Where did i go wrong?
here is what i managed to come up with:
SELECT p.*, f.name, l.quantity
FROM person_product AS l
INNER JOIN people_table AS p ON l.person_id=p.id
INNER JOIN product_table AS f ON l.product_id=f.id
ORDER BY id`
It seems that you're generating a report of all people, against all products with the relevant quantity; on a large data set this could take a while as you're not specifically joining product to person for anything other than quantity:
SELECT
p.id,
p.name,
p.gender,
f.name,
IFNULL(l.quantity,0) AS quantity
FROM person_table AS p
JOIN product_table AS f
LEFT JOIN person_product AS l
ON l.person_id = p.id
AND l.product_id = f.id
ORDER BY p.id, f.name
Which results in:
Is that more-or-less what you're after?
you need to start with people_table than using left join you need to bring other table data.
as you need 0 value if null than you can use function IFNULL
SELECT p.*, f.name, IFNULL(l.quantity,0)
FROM people_table AS p
LEFT JOIN person_product AS l ON l.person_id=p.id
LEFT JOIN product_table AS f ON l.product_id=f.id
ORDER BY p.id
if has no book shouldn't appear in the table , try this (easy to understand) :
SELECT NAME
,'0'
,'0'
FROM person_table
WHERE id NOT IN (
SELECT person_id
FROM person_product
)
UNION
SELECT person_id
,product_id
,quantity
FROM person_product;
I am trying to select distinct rows within my SQL table, however I'm not having luck in labeling the returned rows appropriately using the code below:
SELECT #row:=#row+1 as rank,
a.id,
a.name
FROM table a,
( SELECT #row:=0) b
GROUP BY a.id
ORDER BY a.name ASC
This query will return the following:
| RANK | ID | NAME
--------------------------
2 | 4483 | Bob
8 | 9453 | Joe
10 | 4543 | Maurice
What I want it to return is this, however:
| RANK | ID | NAME
--------------------------
1 | 4483 | Bob
2 | 9453 | Joe
3 | 4543 | Maurice
Would it be more appropriate for me to use a DISTINCT query for a query of this magnitude?
As per Marc B's solution, I decided to wrap my query with another one however instead I decided to Select DISTINCT columns rather than grouping them which would remove my margin of error, by using this code
SELECT #row:=#row+1 as rank, a.id, a.name FROM
(
SELECT DISTINCT id, name
FROM Table1
) a, (SELECT #row:=0) b
ORDER BY a.name ASC
Im not very familiar with using 'join' in queries. I really tried solving this by my own, but it seems to be too hard.
I got 2 Tables:
Table 'users':
+-----------------+-----------------+
| member | online |
+-----------------+-----------------+
| mahran | 1 |
| peter | 1 |
| Jen | 1 |
| Steve | 0 |
+-----------------+-----------------+
Table 'tickets'
+-----------------+----------------+----------------+
| name | category | time |
+-----------------+----------------+----------------+
| mahran | silver | 1 |
| peter | blue | 1 |
| mahran | blue | 2 |
| peter | red | 3 |
| peter | green | 2 |
| Jen | silver | 1 |
+-----------------+----------------+----------------+
The chellange:
I need each member (users.member) who's online (users.online). The next thing is to get the category for each member (user.member = tickets.name) with the highest time (probably ORDER BY time DESC LIMIT 1).
So, for example:
Peter is online. Peters highest time is 3 at the position of category=red. So I want peter to show up in the result with his category 'red'. Mahran would show up with blue. Jen would get silver. And steve would be left out because he's not online.
I hope this was clear. In general I know how the queries would look like but theres no chance for me merging them together.
What needs to be merged:
SELECT member FROM users WHERE online = 1;
|
v for each member
SELECT category FROM tickets WHERE name=users.member ORDER BY time DESC.
So, any ideas how to solve this?
Here is a fiddle with a not working query: Click
You can do this easily with a correlated subquery:
select u.member,
(select t.category
from tickets t
where t.name = u.member
order by t.time desc
limit 1
) as MostRecentCategory
from users u
where u.online = 1;
This can make use of the following indexes: users(online, member) and ticket(member, time, category).
Here is the query you're looking for:
SELECT U.member
,T.category
FROM users U
INNER JOIN tickets T ON T.name = U.member
INNER JOIN (SELECT T2.name
,MAX(T2.time) AS [maxTime]
FROM tickets T2
GROUP BY T2.name) AS M ON M.name = T.name
AND M.maxTime = T.time
WHERE U.online = 1
The use of [name] to join the two tables is not a good practice, it's much better to use keys instead. But my query is just here to help you understanding the process of jointure.
Hope this will help you.
If i understand you correctly
SELECT DISTINCT users.member, tickets.category FROM tickets JOIN users ON users.member = tickets.name WHERE users.online = 1 ORDER BY tickets.time DESC
Can you make sql fiddle?
USE DISTINCT
stackoverflow.com/questions/11704012/mysql-distinct-join
try this
SELECT DISTINCT User.member,Ticket.category FROM users AS USER
INNER JOIN tickets AS Ticket ON (User.member = Ticket.name)
WHERE User.online = 1;
Sorry, but peter seems to be RED, It's time is 3. Don't you?
Depending on table definition, is not guaranteed to have one only result for each user.
For example, if peter has time 3 in two categories, you can get one different category depending of the SQL sorting method.
To be sure, tickets.Category and tickets.time must be in a unique key (both toghether, not a unike key for each field)
Assuming that, the Query could be this.
select t2.name, t2.category
from
tickets t2
INNER JOIN (Select
u.member, max(time)
from users u, tickets t
where
u.member = t.name
and u.online = 1
group by u.member
) as usermaxtime on t2.name = usermaxtime.member;
I need to generate some big data from many tables, regarding filters, at there also i need to get the sum of some columns, and also counts of rows like example
i have 5 records
ID | NAME | DELETED
1 | A | 1
2 | A | 0
3 | A | 1
4 | B | 1
5 | C | 1
I have the query,
SELECT p.name, sum(p.deleted) as del, count(p.id) as numbers from products as p
join other AS b ON p.id=b.id
The output i need is,
The sum of deleted records
NAME | Deletion | Count
A | 2 | 3
B | 1 | 1
C | 1 | 1
Try this ::
SELECT
p.name,
sum(p.deleted) as del,
count(id) as numbers
from products as p
join other AS b ON p.id=b.id
group by p.name
You should not need to join to get your result. This should work:
SELECT name, sum(deleted), count(1)
FROM products
GROUP BY name
SELECT name,
SUM(CASE WHEN deleted = 1 THEN 1 ELSE 0 END) Deletion,
COUNT(*) `COunt`
FROM products
GROUP BY name
OR
SELECT name,
SUM(deleted) Deletion,
COUNT(*) `COunt`
FROM products
GROUP BY name;
SQLFiddle Demo (both queries)