How to write the SQL query? - sql

Suppose I have the following table, How can I write the SQL query to find a set of results which are the minimum c for each b? for example, I want (7, 45) and (16, 69) for the following table.
a | b | c
-----+--------+----
3 | 7 | 53
2 | 7 | 49
1 | 7 | 45
5 | 7 | 61
13 | 16 | 69
15 | 16 | 77
6 | 7 | 65
4 | 7 | 57
14 | 16 | 73


Just use GROUP BY:
SELECT b, MIN(c)
FROM yourTable
GROUP BY b


You can do this using distinct on in Postgres:
select distinct on (b) b, c
from t
order by b, c asc;
An alternative is group by:
select b, min(c)
from t
group by b;
You can try both and see which is faster.

Related

How to count how many times a specific value appeared on each columns and group by range

I'm new on postgres and I have a question:
I have a table with 100 columns. I need to count the values from each columns and count how many times they appeared, so I can group then based on the range that they fit
I have a table like this(100 columns)
+------+------+------+------+------+---------+--------+
| Name | PRB0 | PRB1 | PRB2 | PRB3 | ....... | PRB100 |
+------+------+------+------+------+---------+--------+
| A | 15 | 6 | 47 | 54 | ..... | 8 |
| B | 25 | 22 | 84 | 86 | ..... | 76 |
| C | 57 | 57 | 96 | 38 | ..... | 28 |
+------+------+------+------+------+---------+--------+
And need the output to be something like this
+------+---------------+----------------+----------------+----------------+-----+-----------------+--+
| Name | Count 0 to 20 | Count 21 to 40 | Count 41 to 60 | Count 61 to 70 | ... | Count 81 to 100 | |
+------+---------------+----------------+----------------+----------------+-----+-----------------+--+
| A | 5 | 46 | 87 | 34 | ... | 98 | |
| B | 5 | 2 | 34 | 56 | ... | 36 | |
| C | 7 | 17 | 56 | 78 | ... | 88 | |
+------+---------------+----------------+----------------+----------------+-----+-----------------+--+
For Name A we have:
5 times the number between 0 and 20 apeared
46 times the number between 21 and 40 appeared
86 times the number between 41 and 60 appeared
Basicaly I need something like the function COUNTIFS that we have on Excel. On excel we just need to especify the range of columns and the condition.

You could unpivot with a lateral join, then aggregate:
select
name,
count(*) filter(where prb between 0 and 20) cnt_00_20,
count(*) filter(where prb between 21 and 50) cnt_21_20,
...,
count(*) filter(where prb between 81 and 100) cnt_81_100
from mytable t
cross join lateral (values(t.prb0), (t.prb1), ..., (t.prb100)) p(prb)
group by name
Note, however, that this still requires you to enumerate all the columns in the values() table constructor. If you want something fully dynamic, you can use json instead. The idea is to turn each record to a json object using to_jsonb(), then to rows with jsonb_each(); you can then do conditional aggregation.
select
name,
count(*) filter(where prb::int between 0 and 20) cnt_00_20,
count(*) filter(where prb::int between 21 and 50) cnt_21_20,
...,
count(*) filter(where prb::int between 81 and 100) cnt_81_100
from mytable t
cross join lateral to_jsonb(t) j(js)
cross join lateral jsonb_each( j.js - 'name') r(col, prb)
group by name

How to increment grouping number in query if consecutive values don't satisfy conditions defined?

I will describe problem briefly.
----------------------------------------------------------------------------------------------------
| Total UnitName UnitValue PartlyStatus PartlyValue CountMetric CountValue | RowNo
| |
| 79 A 7654 B 0 C 360 | 1
| 79 A 7656 B 0 C 360 | 2
| 79 A 7657 B 0 C 360 | 2
| 79 A 7658 B 0 C 360 | 2
| 79 A 7659 B 1 C 240 | 3
| 79 A 7660 B 0 C 360 | 4
| 79 A 7662 B 1 C 240 | 5
| 79 A 7663 B 1 C 240 | 5
| 79 A 7664 B 1 C 240 | 5
| 79 A 7665 B 1 C 240 | 5
| 79 A 7667 B 1 C 240 | 6
| 79 A 7668 B 1 C 240 | 6
| 79 A 7669 B 1 C 240 | 6
| 79 A 7670 B 0 C 360 | 7
| 79 A 7671 B 0 C 360 | 7
| 79 A 7672 B 0 C 360 | 7
---------------------------------------------------------------------------------------------------
I have to create new row in my table in SQL Server Reporting Services(SSRS) if constraint is not satisfied.
Rules that i have to apply:
If UnitValue Numbers are not consecutive, use next row.
If binary values of partlyValue changes, use next row.
I have to write a query that creates a RowNo, which increments if conditions are not satisfied.
The table that i show is a derived result from long query to demonstrate problem. RowNo column is written for showing intended result.
My question is asked for understanding and thinking about elegant approaches to solve problem,
so conceptual query examples or solutions are fine for me as long as it puts me in a right direction.

I think you just want window functions. It is a little hard to follow the logic but this does what you want:
select t.*,
sum(case when prev_uv = unitvalue - 1 and
prev_pv = partlyvalue
then 0 -- no new group
else 1
end) over (order by unitvalue) as rowno
from (select t.*,
lag(unitvalue) over (order by unitvalue) as prev_uv,
lag(partlyvalue) over (order by unitvalue) as prev_pv
from t
) t;

You need to write functions in your solution explorer.

How to count all distinct rows?

If I have a table like below, how can I count and sum all distinct values?
student_name | section | score | class
-------------|---------|-------|-------
John | B | 32 | 8
Doe | B | 43 | 8
Jane | A | 33 | 8
Smith | A | 88 | 8
Pat | B | 99 | 9
The output I desire is following for each class. So for class 8 it would be:
section | num_records | score_total
---------|--------------|-------------
B | 2 | 75
A | 2 | 121
Total | 4 | 196

You could use GROUPING SETS:
SELECT COALESCE(section, 'Total') AS section,
COUNT(*) AS num_records,
SUM(score) AS score_total
FROM t
WHERE class = 8
GROUP BY GROUPING SETS (section, ())
ORDER BY section;
db<>fiddle demo

you could use union all and subquery
select section,count(*),sum(score)
from t
where class =8
group by section
union all
select 'Total',count(*),sum(score) from t
where class=8
demo
output
section count sum
A 2 121
B 2 75
Total 4 196

How to use previous row's column's value for calculating the next row's column's value

I have a table
Id | Aisle | OddEven | Bay | Size | Y-Axis
3 | A1 | Even | 14 | 10 | 100
1 | A1 | Even | 16 | 10 |
6 | A1 | Even | 20 | 10 |
12 | A1 | Even | 26 | 5 | 150
10 | A1 | Even | 28 | 5 |
11 | A1 | Even | 32 | 5 |
2 | A1 | Odd | 13 | 10 | 100
5 | A1 | Odd | 17 | 10 |
4 | A1 | Odd | 19 | 10 |
9 | A1 | Odd | 23 | 5 | 150
7 | A1 | Odd | 25 | 5 |
8 | A1 | Odd | 29 | 5 |
want to look like this
Id | Aisle | OddEven | Bay | Size | Y-Axis
1 | A1 | Even | 14 | 10 | 100
2 | A1 | Even | 16 | 10 | 110
3 | A1 | Even | 20 | 10 | 120
4 | A1 | Even | 26 | 5 | 150
5 | A1 | Even | 28 | 5 | 155
6 | A1 | Even | 32 | 5 | 160
7 | A1 | Odd | 13 | 10 | 100
8 | A1 | Odd | 17 | 10 | 110
9 | A1 | Odd | 19 | 10 | 120
10 | A1 | Odd | 23 | 5 | 150
11 | A1 | Odd | 25 | 5 | 155
12 | A1 | Odd | 29 | 5 | 160
I need a select query and update query. What its doing is there are already some Y-Axis Number been filled (at the start of the Odd/Even) then I need to take the previous row's Y-Axis column's value and adds to the current rows's size which = to current Y-Axis. Needs to keep doing it until it finds another Y-Axis has the value it skips the calculation and next row is using that number.
My thinking process is this:
Id will definitely be used, however, the Id is not sequence as shown my example
so I need to have
ROW_Number OVER (PARTITION BY Aisle,OddEven,Bay Order BY Aisle,OddEven,Bay)
Then some kind of JOIN the same table but the ON is T1.RN = T2.RN - 1
Where I am stuck is but the first row has not previous value it will try to update that value.
Anyone have an idea for SQL Query 2008 for Select and Update will be greatly appreciated! Thanks.

You seem to want a cumulative sum. This would be easier in SQL Server 2012+. You can do this in SQL Server 2008 using outer apply:
select t.*, cume_value
from t outer apply
(select sum(size) + sum(yaxis) as cume_value
from t t2
where t2.aisle = t.aisle and t2.oddeven = t.oddeven and
t2.bay < t.bay
) t2;

A little more difficult on 2008, but I think this is what you are looking for
Declare #Table table (Id int,Aisle varchar(25),OddEven varchar(25),Bay int,Size int,[Y-Axis] int)
Insert Into #Table values
(3,'A1','Even',14,10 ,100),
(1,'A1','Even',16,10 ,0),
(6,'A1','Even',20,10 ,0),
(12,'A1','Even',26,5,150),
(10,'A1','Even',28,5,0),
(11,'A1','Even',32,5,0),
(2,'A1','Odd',13,10 ,100),
(5,'A1','Odd',17,10 ,0),
(4,'A1','Odd',19,10 ,0),
(9,'A1','Odd',23,5,150),
(7,'A1','Odd',25,5,0),
(8,'A1','Odd',29,5,0)
;with cteBase as (
Select *
,IDNew=Row_Number() over (Order By Aisle,Bay)
,RowNr=Row_Number() over (Order By Aisle,OddEven,Bay)
From #Table
)
, cteGroup as (Select TmpRowNr=RowNr,GrpNr=Row_Number() over (Order By RowNr) from cteBase where [Y-Axis]>0)
, cteFinal as (
Select A.*
,GrpNr = (Select max(GrpNr) from cteGroup Where TmpRowNr<=RowNr)
From cteBase A
)
Select ID=Row_Number() over (Order By A.OddEven,A.Bay)
,A.Aisle
,A.OddEven
,A.Bay
,A.Size
,[Y-Axis] = Sum(case when B.[Y-Axis]>0 then B.[Y-Axis] else B.Size end)
From cteFinal A
Join cteFinal B on (B.RowNr<=A.RowNr and A.GrpNr=B.GrpNr)
Group By
A.IDNew
,A.Aisle
,A.OddEven
,A.Bay
,A.Size
Order By A.OddEven,A.Bay
Returns
ID Aisle OddEven Bay Size Y-Axis
1 A1 Even 14 10 100
2 A1 Even 16 10 110
3 A1 Even 20 10 120
4 A1 Even 26 5 150
5 A1 Even 28 5 155
6 A1 Even 32 5 160
7 A1 Odd 13 10 100
8 A1 Odd 17 10 110
9 A1 Odd 19 10 120
10 A1 Odd 23 5 150
11 A1 Odd 25 5 155
12 A1 Odd 29 5 160

I gotta leave my computer so update query should be easy to move on from here.
Below is the select query;
select row_number() over (order by oddeven,bay) id,
Aisle,
OddEven,
Bay,
Size,
max(ISNULL([Y-Axis],0)) over (partition by Aisle, OddEven,Size order by bay)
+ sum(CASE WHEN [Y-Axis] is null THEN Size ELSE 0 END) over (partition by Aisle,OddEven,size order by Bay) as [Y-Axis]
from oddseven
order by id

Can I order by multiple columns and somehow keep the ordering related between columns in MySQL?

I know the title doesn't explain my question very well (if someone can come up with a better title then please edit it). Here's what I want to do, say I have the following table:
id | a | b | c
------------------
1 | 3 | 3 | 3
2 | 20 | 40 | 30
3 | 40 | 30 | 10
4 | 30 | 10 | 15
5 | 10 | 15 | 6
6 | 15 | 6 | 20
This is slightly truncated version, I have a few more columns to sort by, but the principle behind the data & my question is the same.
What I would like is to get the data ordered in the following way:
The row with the highest value in col a
The row with the highest value in col b
The row with the highest value in col c
Followed by all remaining rows ordered by their value in col c
So, the result set would look like:
id | a | b | c
------------------
3 | 40 | 30 | 10
2 | 20 | 40 | 30
6 | 15 | 6 | 20
4 | 30 | 10 | 15
5 | 10 | 15 | 6
1 | 3 | 3 | 3
Doing a
SELECT id, a, b, c
FROM table
ORDER BY a DESC, b DESC, c DESC
Obviously gives me a ordered first, then b and finally c, so the following (which is not what I need):
id | a | b | c
------------------
3 | 40 | 30 | 10
4 | 30 | 10 | 15
2 | 20 | 40 | 30
6 | 15 | 6 | 20
5 | 10 | 15 | 6
1 | 3 | 3 | 3

I'm not familiar with the MySQL TSQL dialect but you would have to first SELECT the row with the highest 'A' value, perform a UNION ALL (i.e. no distinct via sorting) with the row with the highest 'B' value, perform a UNION ALL with the row with the highest 'C' value and then a UNION ALL with the remaining rows ordered by 'C' and excluding the 3 rows (by id) already selected.

I've just tested the following which appears to work (does involve 3 subqueries however):
SELECT id, a, b, c
FROM test
ORDER BY FIELD(a,(SELECT MAX(a) FROM test)) DESC,
FIELD(b,(SELECT MAX(b) FROM test)) DESC,
FIELD(c,(SELECT MAX(c) FROM test)) DESC,
c DESC