I have this table
**applications**
id user_id company_id shortlisted
1 10 99 0
2 10 100 1
3 10 101 1
4 10 102 0
5 11 99 1
6 12 99 0
6 12 101 0
What I want is to select all users
which have been shortlisted at-least once
which have not been shortlisted at all
For the first case, i have the following query:
SELECT user_id
from applications
where shortlisted=1
Group
By user_id
and this gives me the expected result like below
**applications**
user_id
10
11
But I'm trying the following query for the second case and it returns me an empty set:
Select user_id
from applications as Application
where shortlisted=0
and NOT EXISTS(Select user_id from applications where user_id=Application.user_id and shortlisted=1)
What am i missing?
PS: Please ignore any typos as i typed them manually for this post.
To get both results in a single query simply use aggregation:
select user_id, max(shortlisted) as was_shortlisted
from applications
group By user_id
You can use group by and having for both.
For the first:
select user_id
from applications
group By user_id
having max(shortlisted) = 1;
For the second:
select user_id
from applications
group By user_id
having max(shortlisted) = 0;
In all honesty, your version with the where is more efficient for the first query. This is just to show how closely related the queries are.
You can try following query;
select user_id from table1
group by user_id having MIN(shortlisted) = 1
This will give you to at least have shortlisted = 1 condition and don't have shortlisted = 0 records.
Related
I have the following data,
id emp_id csa_taken
1 100 2
2 100 2
3 100 0
4 100 2
5 101 2
6 101 2
7 101 0
8 101 0
I expect a result with count where csa_taken=2 for individual employee.
expected result:
emp_id count_csa_taken
100 3
101 2
I have tried the following query with a failed attempt.
Select count(employee_id) From $employeeCSA where csa_taken=2
Please suggest as I am new to sql.
If I understand you correctly you like to count all employees with a cas_taken of two. As there are multiple entries for the csa_taken for one employee you need to group them.
E.g.:
SELECT COUNT(*) FROM $employeeCSA WHERE csa_taken = 2 GROUP_BY employee_id
Please note that COUNT(*) counts the rows (not the fields).
You also need group by. Try like:
Select count(employee_id),emp_id From $employeeCSA where csa_taken=2
group by emp_id
If i understand correctly, then you can try this:
SELECT emp_id,COUNT(emp_id) from dbo.Sample WHERE csa_token = 2 GROUP BY emp_id
I have a table called order_status_log, which logs who changed order statuses.
Simplified table and query below:
order_id user_id status time
1 1 1 2016-01-27 19:35:44
2 2 2 2016-01-27 19:36:45
4 3 2 2016-01-27 19:37:43
2 1 5 2016-01-27 19:38:41
I also have SQL which counts changes by each user:
SELECT
COUNT(*) as count,
user_id
FROM order_status_log
WHERE status = 1
GROUP BY user_id
ORDER BY count
Now I want to improve my query to count only first status changes in order.
In other words I need unique order_id with older time.
How I can change my query to do that?
Something like this?
SELECT *
FROM order_status_log o
WHERE NOT EXISTS
( SELECT 'x'
FROM order_status_log o2
WHERE o2.user_id = o.user_id
AND o2.time < o.time)
How can I count the total number of records, the number of unique of users and number of records on which the status is 2 from the table participants in one query?
I know how to accomplish this using 3 separate queries:
SELECT COUNT() FROM participants
SELECT COUNT() FROM participants GROUP BY user
SELECT COUNT(*) FROM participants WHERE status = 2
But this doesn't really seem efficient?
Table participants
id user status
10 john#example.com 1
11 john#example.com 1
12 john#example.com 1
13 sally#mailing.com 1
14 sally#mailing.com 2
15 edward#halloworld.com 1
16 edward#halloworld.com 1
17 edward#halloworld.com 2
18 mike#bestmail.net 2
19 mike#bestmail.net 1
29 nat#worldcom.com 0
Just use conditional aggregation:
select count(*) as numrecords, count(distinct user) as numusers,
sum(status = 2) as numstatus_2
from participants p;
Since you want just one result (per requirement), you don't need a group by clause at all, and all of these requirements can be created as arguments for the count function:
SELECT COUNT(*) AS total_records,
COUNT(DISTINCT user) AS distinct_users_count,
COUNT(CASE status WHEN 2 ELSE NULL END) AS status_2_count
FROM participants
I have the following table structure for notifications table.
id user_id post_id type status date seconduser_id
1 1 23 1 0 somedate 4
2 2 25 2 0 somedate 3
3 3 26 1 0 somedate 4
4 4 28 2 1 somedate 5
5 5 21 2 0 somedate 4
---
---
and so on
Here type = 1 means a like and type = 2 means a comment. status = 0 means seconduser_id hasn't seen the notification yet. seconduser_id is the notification recipient.
Is it possible to get notifications for 1 user (example seconduser_id = 4), with notification grouped by type, showing count and the latest user_id for each type (in one query)?
The implementation of this would be something like User3 and 10 other people liked your post.
Edit: So far I have something that pulls all notification for user 4 and then groups in php. I don't think this is efficient and so am looking for better solutions.
The basic answer is an aggregation query. The complication is getting the latest user id for each type. THere is one method, using substirng_index()/group_concat():
select type, count(*),
substring_index(group_concat(user_id order by id desc), ',', 1) as latest_user
from notifications n
where secondaryuser_id = 4 and status = 0
group by type;
I am not sure if you also want to filter by status.
Edit (added by OP):
Using the above code and grouping by both post_id and type. Because you want to say User1 and 10 others liked your post. Which means for each grouped notification, post_id has to be unique.
SELECT *, substring_index(group_concat(user_id order by id desc), ',', 1) as latest_user, COUNT(post_id) AS total
FROM notifications n
WHERE seconduser_id = 4 and status = 0
GROUP BY post_id, type
Try this:
SELECT MAX(user_id) AS LatestUser, type, COUNT(type) AS total
FROM notifications
WHERE seconduser_id = 4
GROUP BY type
So I have seen this done with multiple tables, but am confused as to how this would work with multiple tables. I want to select the number of correct entries in a tournament. This works except if a user got none right. Then it returns NULL. I want this to return 0.
Table-tournament_entries
Column
=============
id
tournament_id
game_id
user_id
username
prediction
correct
Here is the query that I run, I am hoping to return all users even the ones who did not get any questions right.
SELECT
tournament_id, username, user_id, COUNT(`prediction`)
FROM
tournament_entries
WHERE
correct = 1 AND tournament_id = 1
GROUP BY
username
ORDER BY
COUNT(`prediction`) DESC
LIMIT 0,10
EDIT: Sorry for all the confusion so when I run my query I get this
username user_id CorrectAns
mj 455 10
charlie 1 8
bill 2 8
doug 51 7
but there are users who are not show who have received 0 right. When I run the queries suggested I receive the number of questions .
username user_id CorrectAns
mj 455 16
charlie 1 16
bill 2 16
doug 51 16
sydney 452 16
Joe 218 16
If you notice sydney and joe are not in the first output but are in the second one
Use this query:
$query ="SELECT tournament_id, username, user_id, COALESCE(COUNT(`prediction`),0) as cpred
FROM tournament_entries
WHERE tournament_id = 1
GROUP BY username
ORDER BY cpred DESC
LIMIT 0,10"
COALESCE will return the first non-null parameter given to it.
Cheers.
Based on your comments to the other answer, I think what you're actually looking for is something like this (although it's hard to be sure without sample data and output):
SELECT
username, user_id, Sum(correct) As TotalCorrect
FROM
tournament_entries
WHERE
tournament_id = 1
GROUP BY
username, user_id
ORDER BY
TotalCorrect DESC
LIMIT 0,10