I'm trying to wrangle an existing database without resorting to tricks. I need to query within a linking table to find all matching id's recursively.
I've tried a number of nested join queries, but I'm not a SQL expert. I'm a programmer and while I work with simple databases complex queries like this are a struggle for me.
My table looks like this:
------------------------
| child_id | parent_ id|
________________________
2 16
3 16
4 16
11 10
12 11
16 7
17 10
18 17
19 7
20 19
21 10
22 21
23 22
24 22
26 20
I only know the top-level parent id. I want to find all associated child ID's.
If the parent ID was 7, I need to return 16,19,2,3,4,20,26.
NOTE: This solution will work in MariaDB 10.2.2 and above.
Try Common Table Expression:
with recursive cte(child_id, parent_id) as (
select child_id, parent_id from MyTable
where parent_id = 7
union all
select mt.child_id, mt.parent_id from MyTable mt
inner join cte t on mt.parent_id = t.child_id
)
select * from cte;
Related
I have 2 tables with identical columns. Is there a way I can append them together. For example if my tables are:
Table 1:
ID Age
1 21
2 26
3 19
4 40
Table 2:
ID Age
6 29
8 40
10 35
I'd like the desired output to be:
ID Age
1 21
2 26
3 19
4 40
6 29
8 40
10 35
Is there a way I can append these 2 tables. Being new to SQL I tried using insert but couldn't do much about it.
Would be great if some one can help out
You can use a UNION ALL query:
SELECT ID, Age
FROM table1
UNION ALL
SELECT ID, Age
FROM table2
This will return all rows from each table in a single result. Here is a demo.
Use Union rather Union All if you want unique values based on two tables.
https://stackoverflow.com/a/49928/2745294
SELECT ID, Age
FROM table1
UNION
SELECT ID, Age
FROM table2
I have the table PERSONAL
ID_PERS NAME
---------------
11 azerty
22 uiop
and the table TOURNE_LABEL
ID_TOUR NAME
--------------
1 w
2 p
3 v
I want to loop over all of person and then join it with tourne and insert to a new table.
I have created empty table LS_PDA
ID_PERS ID_TOURN
-------------------
11 1
11 2
11 3
22 1
22 2
22 3
how can I do that ?
SQL is all about set based operations. If you're thinking about a loop, chances are you're heading in the wrong direction. For this problem, you could cross-join the tables, thus producing all the possible combinations, and use the insert-select syntax:
INSERT INTO ls_pda
SELECT id_pres, id_tour
FROM personal
CROSS JOIN tourne_label
I've searched for adding multiple AVG calculations and have found a few entries, however I'm having to join another table and the examples of that are scarce.
closest answer I can find is this
but it deals with dates and no joins
here are my tables:
indicators:
StandardScore IndicatorID NID DID
0.033333 7 1 1
0.907723 9 1 1
0.574739 26 1 1
0.917391 21 1 1
.....
indexindicators:
IndexID IndicatorID
1 7
1 26
2 21
3 7
4 9
4 21
4 7
5 9
.......
My goal is to get the average for each IndexID (indexindicators) related to NID/DID (indicators) combination
a query to retrieve a single value would be
SELECT AVG(StandardScore) FROM `indicators` INNER JOIN indexindicators ON indicators.IndicatorId=indexindicators.IndicatorId WHERE nid=1 AND did=1 AND indexindicators.IndexId=1
ultimately there will be 6 (indexID) averages which then have to be rounded then * by 100 (should I do that part with PHP?)
This seems like such a simple query, but i just can't seem wrap my mind around it.
Thanks in advance for your help!
SELECT nid, did, indexid, 100.0 * AVG(StandardScore)
FROM 'indicators'
INNER JOIN 'indexindicators'
ON indicators.IndicatorId=indexindicators.IndicatorId
group by nid, did, indexid
I'm trying to get a Group ID key from a bridge table that looks something like this:
GROUP_KEY DIM_KEY
1 11
1 12
1 13
1 14
2 11
2 12
3 11
3 12
3 13
3 15
4 11
5 11
5 12
5 13
I've searched a little bit a got this query:
SELECT b1.group_key
FROM BRIDGE b1
JOIN BRIDGE b2 ON (b1.group_key= b2.group_key)
JOIN BRIDGE b3 ON (b1.group_key= b3.group_key)
WHERE b1.dim_key = 11
AND b2.dim_key = 12
AND b3.dim_key = 13;
But this gets me 1,3 and 5, and I only want the 5, I can filter it further with a a count = 3, but my question is, is there a better way ? I'm using PL/SQL btw.
EDIT
if you are using Oracle 11g, try the following
SELECT group_key FROM (
SELECT GROUP_KEY, listagg(DIM_KEY, ',') WITHIN GROUP(ORDER BY DIM_KEY) DIM_KEY
FROM t
GROUP BY GROUP_KEY) WHERE dim_key = '11,12,13'
I don´t really know what you want. But if you want to the count to be 3. Then you can do it like this:
WITH CTE
(
SELECT
COUNT(GROUP_KEY) OVER(PARTITION BY GROUP_KEY) AS Counts,
BRIDGE.*
FROM
BRIDGE
)
SELECT
*
FROM
CTE
WHERE
CTE.Counts=3
AND CTE.dim_key IN(11,12,13);
Image you are creating a DB schema for a threaded discussion board. Is there an efficient way to select a properly sorted list for a given thread? The code I have written works but does not sort the way I would like it too.
Let's say you have this data:
ID | ParentID
-----------------
1 | null
2 | 1
3 | 2
4 | 1
5 | 3
So the structure is supposed to look like this:
1
|- 2
| |- 3
| | |- 5
|- 4
Ideally, in the code, we want the result set to appear in the following order: 1, 2, 3, 5, 4
PROBLEM: With the CTE I wrote it is actually being returned as: 1, 2, 4, 3, 5
I know this would be easy to group/order by using LINQ but I am reluctant to do this in memory. It seems like the best solution at this point though...
Here is the CTE I am currently using:
with Replies as (
select c.CommentID, c.ParentCommentID 1 as Level
from Comment c
where ParentCommentID is null and CommentID = #ParentCommentID
union all
select c.CommentID, c.ParentCommentID, r.Level + 1 as Level
from Comment c
inner join Replies r on c.ParentCommentID = r.CommentID
)
select * from Replies
Any help would be appreciated; Thanks!
I'm new to SQL and had not heard about hierarchyid datatype before. After reading about it from this comment I decided I may want to incorporate this into my design. I will experiment with this tonight and post more information if I have success.
Update
Returned result from my sample data, using dance2die's suggestion:
ID | ParentID | Level | DenseRank
-------------------------------------
15 NULL 1 1
20 15 2 1
21 20 3 1
17 22 3 1
22 15 2 2
31 15 2 3
32 15 2 4
33 15 2 5
34 15 2 6
35 15 2 7
36 15 2 8
I am sure that you will love this.
I recently find out about Dense_Rank() function, which is for "ranking within the partition of a result set" according to MSDN
Check out the code below and how "CommentID" is sorted.
As far as I understand, you are trying to partition your result set by ParentCommentID.
Pay attention to "denserank" column.
with Replies (CommentID, ParentCommentID, Level) as
(
select c.CommentID, c.ParentCommentID, 1 as Level
from Comment c
where ParentCommentID is null and CommentID = 1
union all
select c.CommentID, c.ParentCommentID, r.Level + 1 as Level
from Comment c
inner join Replies r on c.ParentCommentID = r.CommentID
)
select *,
denserank = dense_rank() over (partition by ParentCommentID order by CommentID)
from Replies
order by denserank
Result below
You have to use hierarchyid (sql2008 only) or a bunch of string (or byte) concatenation.
Hmmmm - I am not sure if your structure is the best suited for this problem. Off the top of my head I cannot think of anyway to sort the data as you want it within the above query.
The best I can think of is if you have a parent table that ties your comments together (eg. a topic table). If you do you should be able to simply join your replies onto that (you will need to include the correct column obviously), and then you can sort by the topicID, Level to get the sort order you are after (or whatever other info on the topic table represents a good value for sorting).
Consider storing the entire hierarchy (with triggers to update it if it changes ) in a field.
This field in your example would have:
1
1.2
1.2.3
1.2.5
1.4
then you just have to sort on that field, try this and see:
create table #temp (test varchar (10))
insert into #temp (test)
select '1'
union select '1.2'
union select '1.2.3'
union select '1.2.5'
union select '1.4'
select * from #temp order by test asc