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I have T1 table with Id and name columns.
Table T2 with Aggregate_ID and Element_ID.
They are crossed
x1:
ID и Name
1 Car
2 Hood
3 Engine
4 Cylinder
5 Wheel
6 tyre
7 rim (car)
8 Rim fixation (Car)
x2:
Aggregate_ID Element_ID
1 2
1 3
1 4
1 5
3 4
5 6
5 7
7 8
I need to select simplest element like 2, 4, 8
Complexity and number of elements can be varied.
How can I do it with recursion?
There is another task:
I need to output all the simplest elements of which consists Wheel.
Recursive solution in SQL can be very complex. In your case I see no need to use it, since it will only make your code more complex.
You can use CTE if you still insist:
Recursive query in SQL Server
Non- recursive solution:,
You want only the elements that appear in T2 in the Element_ID but not in the Aggregate_ID:
SELECT Element_ID
FROM T2
EXCEPT
SELECT Aggregate_ID
FROM T2
Or if you want to display all of the information for the elements:
SELECT *
FROM T1
WHERE T1.ID NOT IN (SELECT Aggregate_ID
FROM T2)
Related
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I have a table with column name No, which have duplicate values (which is necessary). I need to add an incrementing value in another column sub_no
For Example:
No
sub_no
1
0
1
1
1
2
2
0
2
1
3
0
3
1
3
2
3
3
I have tried update and select queries.
A window function will give you the results you want:
SELECT [No], ROW_NUMBER() OVER(PARTITION BY [No] ORDER BY [No]) - 1 AS
[sub_no]
FROM <table_name>;
You can find more information on window functions in T-SQL here.
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I have the following two tables in PostgreSQL database (simplified for the sake of example):
article
id
summary
1
Article 1
2
Article 2
3
Article 3
...
...
event
id
article_id
eventtype_id
comment
108
1
4
Comment 1
109
2
8
Comment 2
110
3
4
Comment 3
...
...
I would like to select only 1 event with eventtype_id=4 for each article. The result should look like this:
article_id
article_summary
event_comment
1
Article 1
Comment 1
2
Article 2
3
Article 3
Comment 3
...
Which of these 2 queries (Query 1 or Query 2) runs faster? Do they return the same result?
Query1:
SELECT
a.id AS article_id,
a.summary AS article_summary,
evnt.comment AS event_comment
FROM
article a
LEFT JOIN
event evnt ON evnt.article_id = a.id AND evnt.eventtype_id = 4;
Query2:
SELECT
a.id AS article_id,
a.summary AS article_summary,
(
SELECT
evnt.comment
FROM
event evnt
WHERE
evnt.article_id = a.id AND
evnt.eventtype_id = 4
LIMIT 1
) AS event_comment
FROM
article a;
Apart from the fact that queries are not the same, as you said in the comments, generally speaking, correlated queries are not considered suitable from a performance point of view. That's because these queries are applied row by row. They are usually helpful in some particular situations: read this. However, even in those situations, it is a good practice to use them in an exists clause if possible, So that whenever it finds a row for the query it returns true.
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I have a column of values where I need to take the average of the two previous values and the current value and display as a new column. I'm using MS Access 2013 and am more familier using SQL code rather than the SQL Query Wizard. So, if you could provide the code I'd appreciate it.
I've read on other threads that talked about a Lag function, but I believe Access does not allow that. Also, I've seen similar questions answered with subqueries, but I'm not familiar enough with those yet.
Below is what I'm looking for. Given column A (1,2,3,4,5) how do I make B (0,0,2,3,4)?
A | B
----------
1 | 0
2 | 0
3 | 2 = (1+2+3)/3
4 | 3 = (2+3+4)/3
5 | 4 = (3+4+5)/3
Utilize a self join to the same table for when the value of A is BETWEEN a - 2 and A.
SELECT
t.A
,SUM(pre.A) / 3 as B
FROM
TableName t
LEFT JOIN TableName pre
ON pre.A >= (t.A - 2)
AND pre.A <= t.A
GROUP BY
t.A
Note that this will actually give you 0,1,2,3,4. If you want 0,0,2,3,4 you will have to count the preceding rows to determine if there are three and if not make it 0 such as:
SELECT
t.A
,IIF(COUNT(pre.A) < 3, 0, SUM(pre.A) / 3) as B
FROM
TableName t
LEFT JOIN TableName pre
ON pre.A >= (t.A - 2)
AND pre.A <= t.A
GROUP BY
t.A
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I want to assign one unique number for each repeated row in select statement.
table
Name | Position
Mark Wol 1
Mark wol 1
MArtha 1
Martha 1
and I want this
1 Mark Wl 1
2 Martha 1
You can use as few or as many rows as you want. If you want to use all of the rows, list them all.
SELECT Row1, Row2, Row3,
ROW_NUMBER() OVER (
PARTITION BY Row1, Row2, Row3,
ORDER BY Row1
)
FROM Table
The best solution is to already have a unique ID for each record and then you are choosing to show that (which will come from the first found record)...
SELECT name,COUNT(*),id
FROM test_table
GROUP BY name
HAVING COUNT(*) > 1
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ID YEAR FORCE NEIGHBOURHOOD ALL_CRIME ANTI_SOCIAL_BEHAVIOUR BURGLARY CRIMINAL_DAMAGE_AND_ARSON DRUGS OTHER_THEFT PUBLIC_DISORDER_AND_WEAPONS ROBBERY SHOPLIFTING VEHICLE_CRIME VIOLENT_CRIME OTHER_CRIME
1 2013-03 Police AAN_HP 290 91 27 33 11 64 8 6 3 14 27 6
i need to change the order of theses into something like
ID 1
YEAR 2012
FORCE Police
NEIGHBOURHOOD Bradford
ALL_CRIME 12345
ANTI_SOCIAL 87
BURGLARY 10
CRIMINAL_DAMAGE 20
DRUGS 15
OTHER_THEFT 30
If you want to changed the order in which the columns are returning change the order in which you are selecting them
SELECT 1,2,3 FROM t
Would return differently from
SELECT 2,1,3 FROM t
I don't know if this is what you wanted but I found the question confusingly worded!
Quite easy to do with a query:
with lvls as (select /* + materialize */ level lv from dual connect by level <= 9)
select id,
decode(lv,
1,'year',
2,'force'),
...
decode(lv,
1,to_char(year),
2,to_char(force),
...
from yourtable, lvls
order by id,lv;
hint "materialize" will not make Oracle be unperformant (he likes to join here the tables first and then run hierarchy if you do not specify this hint)
try this
select * from your_tab unpivot(col2 for col1 in(ID,YEAR,FORCE,NEIGHBOURHOOD, ALL_CRIME,ANTI_SOCIAL_BEHAVIOUR);
note:All columns mentioned in col1 must be of same datatype