I have following table
ID Name Stage
1 A 1
1 B 2
1 C 3
1 A 4
1 N 5
1 B 6
1 J 7
1 C 8
1 D 9
1 E 10
I need output as below with parameters A and N need to select closest rows where difference between stage is smallest
ID Name Stage
1 A 4
1 N 5
I need to select rows where difference between stage is smallest
This query can make use of an index on (name, stage) efficiently:
WITH cte AS (
SELECT TOP 1
a.id AS a_id, a.name AS a_name, a.stage AS a_stage
, n.id AS n_id, n.name AS n_name, n.stage AS n_stage
FROM tbl a
CROSS APPLY (
SELECT TOP 1 *, stage - a.stage AS diff
FROM tbl
WHERE name = 'N'
AND stage >= a.stage
ORDER BY stage
UNION ALL
SELECT TOP 1 *, a.stage - stage AS diff
FROM tbl
WHERE name = 'N'
AND stage < a.stage
ORDER BY stage DESC
) n
WHERE a.name = 'A'
ORDER BY diff
)
SELECT a_id AS id, a_name AS name, a_stage AS stage FROM cte
UNION ALL
SELECT n_id, n_name, n_stage FROM cte;
SQL Server uses CROSS APPLY in place of standard-SQL LATERAL.
In case of ties (equal difference) the winner is arbitrary, unless you add more ORDER BY expressions as tiebreaker.
dbfiddle here
This solution works, if u know the minimum difference is always 1
SELECT *
FROM myTable as a
CROSS JOIN myTable as b
where a.stage-b.stage=1;
a.ID a.Name a.Stage b.ID b.Name b.Stage
1 A 4 1 N 5
Or simpler if u don't know the minimum
SELECT *
FROM myTable as a
CROSS JOIN myTable as b
where a.stage-b.stage in (SELECT min (a.stage-b.stage)
FROM myTable as a
CROSS JOIN myTable as b)
Related
So I have two tables, both have the same structure:
tableA
tableB
ID
ID
1
1
3
2
5
3
10
5
What I need is to compare tableA.ID and tableB.ID and find out which IDs are free in both table and get the intervals of those free IDs.
To find out free IDs in one table I use this:
SELECT
a.ID + 1 start,
min(b.ID) - 1 end,
min(b.ID) - a.ID - 1 gap
FROM
tableA a,
tableB b
WHERE a.ID < b.ID
GROUP BY a.ID
HAVING start < MIN(b.ID)
It works fine, I get my gaps:
tableA
start
end
gap
2
2
1
4
4
1
6
9
4
tableB
start
end
gap
4
4
1
But then I need to compare the results and check which IDs are free in both tables. The result should look something like this:
start
end
gap
4
4
1
6
9
4
And here I'm honestly lost and I don't have any ideas what to do. I've tried to use join in, but it doesn't work for me:
WHERE a.ID < b.ID AND a.ID IN (
SELECT
c.ID+1 startID,
min(d.ID) - 1 endID,
min(d.ID) - c.ID - 1 gap
from
tableB c,
tableB d
where c.rowid < d.rowid
)
You may union the two tables to get the unique values from both, then use LEAD function to find the free IDs as the following:
WITH reserved_IDs AS
(
SELECT ID FROM tableA
UNION
SELECT ID FROM tableB
UNION SELECT 0 /* To start from 1 in case 1 value is missing from both tables*/
)
SELECT start_id, end_id, gap
FROM
(
SELECT ID+1 AS start_id,
LEAD(ID) OVER (ORDER BY ID) - 1 AS end_id,
LEAD(ID) OVER (ORDER BY ID)-ID-1 gap
FROM reserved_IDs
) T
WHERE gap > 0
See a demo.
I have this table with U that represents "User" and C that represents "Category". I need a way to query how many categories a user has and limit that to 1. So basically, I need to get all the users that has only 1 category. How can this be achieved with SQL (PostgreSQL)?
I've tried to find any solution on Stackoverflow for a while now, but without success.
id U C
1 3 5
2 1 3
3 3 5
4 5 2
5 11 5
6 11 5
Expected result:
id U C
1 1 3
2 5 2
That is easy with the HAVING clause:
SELECT max(id), u, max(c)
FROM atable
GROUP BY u HAVING count(c) = 1
You can use window functions for your purpose.
Window Functions
SELECT DISTINCT * FROM(
SELECT a.*,count(c)over(partition by id) as cnt
FROM testtable a
) WHERE CNT=1
If you have no duplicates, you can use not exists:
select t.*
from t
where not exists (select 1 from t t2 where t2.u = t.u and t2.c <> t.c);
If you have duplicates of u/c, just use id:
select t.*
from t
where not exists (select 1 from t t2 where t2.u = t.u and t2.id <> t.id);
If you want to reassign a sequential number, then use row_number() as well:
select row_number() over (order by id) as new_id, t.*
from t
where not exists (select 1 from t t2 where t2.u = t.u and t2.c <> t.c);
lets say i have a data set of
A B
-- --
a 1
b 1
c 1
d 1
d 2
e 1
f 1
f 2
g 1
how would i exclude a result in column B of 1, if column B has values of both 1 and 2 for the same value in column A?
i want my results to look like this
A B
-- --
a 1
b 1
c 1
d 2
e 1
f 2
g 1
Checking explicitly here for the values 1 and 2 and using the fact that there are exactly two of them. You could potentially make this less cumbersome if it's safe to assume that you always want the highest value.
select
tbl.A,
tbl.B
from
Table1 tbl
left outer join (
select
A
from
Table1
where
B in (1,2)
group by
A
having
count(B) = 2
) mlt on tbl.A = mlt.A
where
(
mlt.A is not null
and tbl.B = 2
) or (
mlt.A is null
and tbl.B = 1
)
Figure out all the A values that have both 1 and 2.
Match those to the table on the A value.
If A is in the subquery, use the B = 2 record. If it isn't, use the B = 1 record.
select
* from tbl where a IN
(
select
a from tbl
group by a
having count(*)>1
)
and b!=1
UNION ALL
select
* from tbl where a IN
(
select
a from tbl
group by a
having count(*)=1
)
For the example data and desired result, the simplest query to achieve the result would be a GROUP BY operation and an aggregate function.
SELECT d.A
, MAX(d.B) AS B
FROM my_data_set d
GROUP BY d.A
ORDER BY d.A
If we are only interested in rows that have a 1 or 2 in column B, we can add a WHERE clause
SELECT d.A
, MAX(d.B) AS B
FROM my_data_set d
WHERE d.B IN (1,2)
GROUP BY d.A
ORDER BY d.A
With the example data, the output is the same.
Both of these statements achieve the specified result. (There is only a single row returned for each distinct value in A.)
Or, for the same the example data, we can return the same result set with a more literal implementation of the specification.
To exclude rows with 1when there is a row with 2 for the same value of A, we can use a NOT EXISTS predicate and a correlated subquery.
SELECT d.A
, d.B
FROM my_data_set d
WHERE ( d.B = 2 )
OR ( d.B = 1 AND
NOT EXISTS ( SELECT 1
FROM my_data_set e
WHERE e.A = d.A
AND e.B = 2
)
)
ORDER BY d.A, d.B
I have the following table:
Name Field
A 1
B 1
C 1
D 1
E 1
F 1
G 1
H 2
I 2
J 2
K 3
L 3
M 3
N 3
O 3
P 3
Q 3
R 3
S 3
T 3
I need a SQL query which will generate me a set with 5 random rows for each distinct value on column Field.
For example, results expected:
Name Field
A 1
B 1
D 1
E 1
G 1
J 2
I 2
H 2
M 3
Q 3
T 3
S 3
P 3
Is there an easy way to do this? Or should i split that table into more tables and generate random for each table then union them?
You can do this with a CTE using a ROW_NUMBER() whilst PARTITIONing on the Field:
;With Cte As
(
Select Name, Field,
Row_Number() Over (Partition By Field Order By NewId()) RN
From YourTable
)
Select Name, Field
From Cte
Where RN <= 5
SQL Fiddle
You can readily do this with row_number():
select name, field
from (select t.*,
row_number() over (partition by field order by newid()) as seqnum
from t
) t
where seqnum <= 5;
An enhancement to Gordon Linoff's code, This code really helped me if you need criteria in your query.
select *
from (select t.*,
row_number() over (partition by region order by newid()) as seqnum
from MyTable t
WHERE t.program = 'ACME'
) t
where seqnum <= 1500;
I have a table_1:
id custno
1 1
2 2
3 3
and a table_2:
id custno qty descr
1 1 10 a
2 1 7 b
3 2 4 c
4 3 7 d
5 1 5 e
6 1 5 f
When I run this query to show the minimum order quantities from every customer:
SELECT DISTINCT table_1.custno,table_2.qty,table_2.descr
FROM table_1
LEFT OUTER JOIN table_2
ON table_1.custno = table_2.custno AND qty = (SELECT MIN(qty) FROM table_2
WHERE table_2.custno = table_1.custno )
Then I get this result:
custno qty descr
1 5 e
1 5 f
2 4 c
3 7 d
Customer 1 appears twice each time with the same minimum qty (& a different description) but I only want to see customer 1 appear once. I don't care if that is the record with 'e' as a description or 'f' as a description.
First of all... I'm not sure why you need to include table_1 in the queries to begin with:
select custno, min(qty) as min_qty
from table_2
group by custno;
But just in case there is other information that you need that wasn't included in the question:
select table_1.custno, ifnull(min(qty),0) as min_qty
from table_1
left outer join table_2
on table_1.custno = table_2.custno
group by table_1.custno;
"Generic" SQL way:
SELECT table_1.custno,table_2.qty,table_2.descr
FROM table_1, table_2
WHERE table_2.id = (SELECT TOP 1 id
FROM table_2
WHERE custno = table_1.custno
ORDER BY qty )
SQL 2008 way (probably faster):
SELECT custno, qty, descr
FROM
(SELECT
custno,
qty,
descr,
ROW_NUMBER() OVER (PARTITION BY custno ORDER BY qty) RowNum
FROM table_2
) A
WHERE RowNum = 1
If you use SQL-Server you could use ROW_NUMBER and a CTE:
WITH CTE AS
(
SELECT table_1.custno,table_2.qty,table_2.descr,
RN = ROW_NUMBER() OVER ( PARTITION BY table_1.custno
Order By table_2.qty ASC)
FROM table_1
LEFT OUTER JOIN table_2
ON table_1.custno = table_2.custno
)
SELECT custno, qty,descr
FROM CTE
WHERE RN = 1
Demolink