I want to select rows that have a distinct Title Column.
Id Title Type
1 Bronze Group
2 Bronze Group
3 Bronze Group
4 Silver Group
5 Silver Group
6 Silver Group
7 Gold Group
8 Gold Group
9 Gold Group
10 Platinum Group
11 Platinum Group
12 Platinum Group
I thought this would be a simple query but i'm struggling! If anyone can help that would be great
SELECT DISTINCT(Title), Id
FROM Package
WHERE Type='Group'
ORDER BY Id ASC
You need to group by the title. And you have to tell the DB which rule to apply when selecting the id for duplicate entries. For instance the smallest id for every unique title:
SELECT Title, min(Id) as minid
FROM Package
WHERE Type='Group'
GROUP BY Title
ORDER BY min(Id) ASC
You have to drop the ID off as it is unique and makes it DISTINCT. Something like this.
SELECT DISTINCT Title
FROM Package
WHERE Type='Group'
Related
i'm introducing you the problem with DISTINCT values by column condition i have dealt with and can't provide
any idea how i can solve it.
So. The problem is i have two Stephen here declared , but i don't want duplicates:
**
The problem:
**
id vehicle_id worker_id user_type user_fullname
9 1 NULL external_users John Dalton
10 1 16 employees Mike
11 1 1 employees Stephen
12 2 173 employee Nicholas
13 2 1 employee Stephen
14 1 NULL external_users Peter
**
The desired output:**
id vehicle_id worker_id user_type user_fullname
9 1 NULL external_users John Dalton
10 1 16 employees Mike
12 2 173 employee Nicholas
13 2 1 employee Stephen
14 1 NULL external_users Peter
I have tried CASE statements but without success. When i group by it by worker_id,
it removes another duplicates, so i figured out it needs to be grouped by some special condition?
If anyone can provide me some hint how i can solve this problem , i will be very grateful.
Thank's!
There are no duplicate rows in this table. Just because Stephen appears twice doesn't make them duplicates because the ID, VEHICLE_ID, and USER_TYPE are different.
What you need to do is decide how you want to identify the Stephen record you wish to see in the output. Is it the one with the highest VEHICLE_ID? The "latest" record, i.e. the one with the highest ID?
You will use that rule in a window function to order the rows within your criteria, and then use that row number to filter down to the results you want. Something like this:
select id, vehicle_id, worker_id, user_type, user_fullname
from (
select id, vehicle_id, worker_id, user_type, user_fullname,
row_number() over (partition by worker_id, user_fullname order by id desc) n
from user_vehicle
) t
where t.n = 1
I have a script
SELECT customer_id, COUNT(*)
FROM devices
GROUP BY customer_id
ORDER BY 2 desc;
and the result is
customer_id count
1234 8
4567 7
8910 7
1112 7
1314 5
1516 5
but what I expect is
devices customer
8 1
7 3
5 2
Is there any way without using a new table?
Use your current query as a source for another:
with temp as
-- this is your current query
(select customer_id,
count(*) cnt
from devices
group by customer_id
)
select cnt as devices,
count(*) as customer
from temp
group by cnt;
The usual use of count(*) is to find out many rows have been aggregated by group function. Want you ant to do is aggregate your result in a second select, and ask for count(*) a second time to get result you've described.
Given a dataset Roster_table as such:
Group ID
Group Name
Name
Phone
42
Red Dragon
Jon
123455678
32
Green Lizard
Liz
932143211
19
Blue Falcon
Ben
134554678
42
Red Dragon
Reed
432143211
42
Red Dragon
Brad
231314155
19
Blue Falcon
Chad
214124412
How do I get the following query output combining rows with the same Group ID from the dataset, and the new column Count in descending order:
Group ID
Group Name
Count
42
Red Dragon
3
19
Blue Falcon
2
32
Green Lizard
1
SELECT * FROM Roster_table
Please try this where alias tot_count is used in ORDER BY clause.
-- PostgreSQL(v11)
SELECT Group_ID
, MAX(Group_Name) Group_Name
, COUNT(1) tot_count
FROM Roster_table
GROUP BY Group_ID
ORDER BY tot_count DESC;
Please check from url https://dbfiddle.uk/?rdbms=postgres_11&fiddle=b66f9f0d40e804e89be12e3530fe00a0
Based on Rahul Biswas's answer:
Solution without using Max function
SELECT Group_ID, Group_Name, COUNT(*)
FROM Roster_table
GROUP BY Group_ID, Group_Name
ORDER BY COUNT(*) DESC
Credit goes to Eric S.
I have a SQL Server 2008 database. In this database, I have a result set that looks like the following:
ID Name Department LastOrderDate
-- ---- ---------- -------------
1 Golf Balls Sports 01/01/2015
2 Compact Disc Electronics 02/01/2015
3 Tires Automotive 01/15/2015
4 T-Shirt Clothing 01/10/2015
5 DVD Electronics 01/07/2015
6 Tennis Balls Sports 01/09/2015
7 Sweatshirt Clothing 01/04/2015
...
For some reason, my users want to get the results ordered by department, then last order date. However, not by department name. Instead, the departments will be in a specific order. For example, they want to see the results ordered by Electronics, Automotive, Sports, then Clothing. To throw another kink in works, I cannot update the table schema.
Is there a way to do this with a SQL Query? If so, how? Currently, I'm stuck at
SELECT *
FROM
vOrders o
ORDER BY
o.LastOrderDate
Thank you!
You can use case expression ;
order by case when department = 'Electronics' then 1
when department = 'Automotive' then 2
when department = 'Sports' then 3
when department = 'Clothing' then 4
else 5 end
create a table for the departments that has the name (or better id) of the department and the display order. then join to that table and order by the display order column.
alternatively you can do a order by case:
ORDER BY CASE WHEN Department = 'Electronics' THEN 1
WHEN Department = 'Automotive' THEN 2
...
END
(that is not recommended for larger tables)
Here solution with CTE
with c (iOrder, dept)
as (
Select 1, 'Electronics'
Union
Select 2, 'Automotive'
Union
Select 3, 'Sports'
Union
Select 4, 'Clothing'
)
Select * from c
SELECT o.*
FROM
vOrders o join c
on c.dept = o.Department
ORDER BY
c.iOrder
I am facing a very common issue regarding "Selecting top N rows for each group in a table".
Consider a table with id, name, hair_colour, score columns.
I want a resultset such that, for each hair colour, get me top 3 scorer names.
To solve this i got exactly what i need on Rick Osborne's blogpost "sql-getting-top-n-rows-for-a-grouped-query"
That solution doesn't work as expected when my scores are equal.
In above example the result as follow.
id name hair score ranknum
---------------------------------
12 Kit Blonde 10 1
9 Becca Blonde 9 2
8 Katie Blonde 8 3
3 Sarah Brunette 10 1
4 Deborah Brunette 9 2 - ------- - - > if
1 Kim Brunette 8 3
Consider the row 4 Deborah Brunette 9 2. If this also has same score (10) same as Sarah, then ranknum will be 2,2,3 for "Brunette" type of hair.
What's the solution to this?
If you're using SQL Server 2005 or newer, you can use the ranking functions and a CTE to achieve this:
;WITH HairColors AS
(SELECT id, name, hair, score,
ROW_NUMBER() OVER(PARTITION BY hair ORDER BY score DESC) as 'RowNum'
)
SELECT id, name, hair, score
FROM HairColors
WHERE RowNum <= 3
This CTE will "partition" your data by the value of the hair column, and each partition is then order by score (descending) and gets a row number; the highest score for each partition is 1, then 2 etc.
So if you want to the TOP 3 of each group, select only those rows from the CTE that have a RowNum of 3 or less (1, 2, 3) --> there you go!
The way the algorithm comes up with the rank, is to count the number of rows in the cross-product with a score equal to or greater than the girl in question, in order to generate rank. Hence in the problem case you're talking about, Sarah's grid would look like
a.name | a.score | b.name | b.score
-------+---------+---------+--------
Sarah | 9 | Sarah | 9
Sarah | 9 | Deborah | 9
and similarly for Deborah, which is why both girls get a rank of 2 here.
The problem is that when there's a tie, all girls take the lowest value in the tied range due to this count, when you'd want them to take the highest value instead. I think a simple change can fix this:
Instead of a greater-than-or-equal comparison, use a strict greater-than comparison to count the number of girls who are strictly better. Then, add one to that and you have your rank (which will deal with ties as appropriate). So the inner select would be:
SELECT a.id, COUNT(*) + 1 AS ranknum
FROM girl AS a
INNER JOIN girl AS b ON (a.hair = b.hair) AND (a.score < b.score)
GROUP BY a.id
HAVING COUNT(*) <= 3
Can anyone see any problems with this approach that have escaped my notice?
Use this compound select which handles OP problem properly
SELECT g.* FROM girls as g
WHERE g.score > IFNULL( (SELECT g2.score FROM girls as g2
WHERE g.hair=g2.hair ORDER BY g2.score DESC LIMIT 3,1), 0)
Note that you need to use IFNULL here to handle case when table girls has less rows for some type of hair then we want to see in sql answer (in OP case it is 3 items).