I am using SQL Server 2012, I have a table called [Area]. This table contains a PK and a ParentPK. The ParentPk references the PK from the same [Area] table recursively. If there is no parent, then null is filled in for ParentPk.
Pk ParentPk
----------------
1 null
2 null
3 1
4 3
...
I know that the ancestor-child relationship is exactly 3 levels deep. In the above example, The Pk:4 has its parentPk:3 and grandParentPk:1.
I want to be able have a SELECT query be in the form:
SELECT GrandParentPk, ParentPk, ChildPk
...
...
...
where ChildPk = <childPk>
Is there a non stored procedure, non recursive solution to achieve this?
If you are always querying using the last child pk, and the hierarchy is always three levels, you can just use two inner joins.
select gp.pk as GrandParentPk, p.pk as ParentPk, c.pk as ChildPk
from Area c
inner join Area p
on c.parentPk = p.pk
inner join Area gp
on p.parentPk = gp.pk
where c.pk = 4
rextester demo: http://rextester.com/MSXTVR55260
returns:
+---------------+----------+---------+
| GrandParentPk | ParentPk | ChildPk |
+---------------+----------+---------+
| 1 | 3 | 4 |
+---------------+----------+---------+
Related
SQL Server 2016
I have a number of tables
Table A Table B Table C Table D
User | DataA User | DataB User | DataC User | DataD
=========== =========== =================== =============
1 | 10 1 | 'hello' 4 | '2020-01-01' 1 | 0.34
2 | 20 2 | 'world'
3 | 30
So some users have data for A,B,C and/or D.
Table UserEnabled
User | A | B | C | D
=============================
1 | 1 | 1 | 0 | 0
2 | 1 | 1 | 0 | 0
3 | 1 | 0 | 0 | 0
4 | 0 | 0 | 1 | 0
Table UserEnabled indicates whether we are interested in any of the data in the corresponding tables A,B,C and/or D.
Now I want to join those tables on User but I do only want the columns where the UserEnabled table has at least one user with a 1 (ie at least one user enabled). Ideally I only want to join the tables that are enabled and not filter the columns from the disabled tables afterwards.
So as a result for all users I would get
User | DataA | DataB | DataC
===============================
1 | 10 | 'hello' | NULL
2 | 20 | 'world' | NULL
3 | 30 | NULL | NULL
4 | NULL | NULL | '2020-01-01'
No user has D enabled so it does not show up in a query
I was going to come up with a dynamic SQL that's built every time I execute the query depending on the state of UserEnabled but I'm afraid this is going to perform poorly on a huge data set as the execution plan will need to be created every time. I want to dynamically display only the enabled data, not columns with all NULL.
Is there another way?
Usage will be a data sheet that may be generated up to a number of times per minute.
You have no choice but to approach this through dynamic SQL. A select query has a fixed set of columns defined when the query is created. No such thing as "variable" columns.
What can you do? One method is to "play a trick". Store the columns as JSON (or XML) and delete the empty columns.
Another method is to create a view that has the specific logic you need. I think you can maintain this view by altering it in a trigger, based on when data in the enabled table changes. That said, altering the view requires dynamic SQL so the code will not be pretty.
Just because I thought this could be fun.
Example
Declare #Col varchar(max) = ''
Declare #Src varchar(max) = ''
Select #Col = #Col+','+Item+'.[Data'+Item+']'
,#Src = #Src+'Left Join [Table'+Item+'] '+Item+' on U.[User]=['+Item+'].[User] and U.['+Item+']=1'+char(13)
From (
Select Item
From ( Select A=max(A)
,B=max(B)
,C=max(C)
,D=max(D)
From UserEnabled
Where 1=1 --<< Use any Key Inital Filter Condition Here
) A
Unpivot ( value for item in (A,B,C,D)) B
Where Value=1
) A
Declare #SQL varchar(max) = '
Select U.[User]'+#Col+'
From #UserEnabled U
'+#Src
--Print #SQL
Exec(#SQL)
Returns
User DataA DataB DataC
1 10 Hello NULL
2 20 World NULL
3 30 NULL NULL
4 NULL NULL 2020-01-01
The Generated SQL
Select A.[User],A.[DataA],B.[DataB],C.[DataC]
From UserEnabled U
Left Join TableA A on U.[User]=[A].[User] and U.[A]=1
Left Join TableB B on U.[User]=[B].[User] and U.[B]=1
Left Join TableC C on U.[User]=[C].[User] and U.[C]=1
If all the relations are 1:1, you can make one query with
...
FROM u
LEFT JOIN a ON u.id = a.u_id
LEFT JOIN b ON u.id = b.u_id
LEFT JOIN c ON u.id = c.u_id
LEFT JOIN d ON u.id = d.u_id
...
and use display logic on the client to omit the irrelevant columns.
If more than one relation is 1:N, then you'd likely have to do multiple queries anyway to prevent N1xN2 results.
In MS Access was very easy to acomplish but I'm having troubles with SQL Server
I have this query:
SELECT Organigrama.Item, Organigrama.Id, Organigrama.ParentItem, Rol_Menu.Cod_Rol
FROM Rol_Menu RIGHT JOIN
Organigrama ON Rol_Menu.Cod_Menu = Organigrama.Id
WHERE (Rol_Menu.Cod_Rol = '5')
The purpose is to get all the items of Organigrama and the elements in common with Rol_Menu.Col_Rol appears with 5, the others with Null
I need to fill a menu structure into a treeview
When the user select another Rol just get nodes checked that rol have access to
im determining if in the row the Col_Rol isn't null so the query I need to get
something like this:
Item | Id | ParentItem | Cod_Rol
A | 3 | null | 5
B | 4 | A | 5
C | 5 | A | null
D | 6 | B | 5
E | 7 | C | null
F | 8 | E | null
I think you just need to include the extra restriction in the join criteria rather then the where clause. The criteria are evaluated before the outer join adds the null columns. The where clause is evaluated afterwards, and eliminates the nulls.
select
Organigrama.Item,
Organigrama.Id,
Organigrama.ParentItem,
Rol_Menu.Cod_Rol
from
Rol_Menu
right join
Organigrama
on Rol_Menu.Cod_Menu = Organigrama.Id and
Rol_Menu.Cod_Rol = '5'
either that or add or Rol_Menu.Cod_Rol is null to the end of the where clause.
I have 2 tables
Bid_customer
|bidkey | customerkey
| 1 | 1
| 1 | 2
| 1 | 3
customer_groups
| groupkey | customerkey
| 1 | 1
| 1 | 2
| 1 | 3
What I'm trying to get is a result that will look like
| bidkey | groupkey
| 1 | 1
I've tried a cursor and joins but just don't seem to be able to get what i need any ideas or suggestions
EDIT: customers can belong to more that one group also
I am not sure who meaningful your sample data is. However following is a simple example.
Query:
select distinct b.bidkey, g.gkey
from bidcus b
inner join cusgroup g
on
b.cuskey = g.cuskey
and g.gkey = 10;
Results:
BIDKEY GKEY
1 10
Reference: SQLFIDDLE
In order to have a working Many-to-Many relationship in a database you need to have an intermediary table that defines the relationship so you do not get duplicates or mismatched values.
This select statement will join all bids with all groups because the customer matches.
Select bidkey, groupkey
From customer_groups
Inner Join bid_customer
Where customer_groups.customerkey = Bid_customer.customerkey
Hers is a sample Many to Many Relationship:
For your question:
You will need another table that joins the data. For example, GroupBids
customer_groups and bid_customer would have a one-to-many relationship with GroupBids
You would then do the following select to get your data.
Select bidkey, groupkey
From bid_customer
inner join GroupBids
ON bid_customer.primarykey = GroupBids.idBidKey
inner join customer_groups
ON customer_groups.primarykey = GroupBids.idCustomerGroupkey
This would make sure only related groups and bids are returned
I'm certain this is very easy, but I am very poor at database stuff...
I have the following table in access 2003:
title | id
/root | 1
/root/x | 2
/root/x/y | 3
/root/x/y/z | 4
/root/x/a | 5
/root/x/a/b | 6
i.e. a bunch of nodes and id numbers - you can see that /root/x is the parent of /root/x/y. I'd like to create another table which has a list of all the nodes, along with the id's of their parents. i.e:
id | parent id
1 | -
2 | 1
3 | 2
4 | 3
5 | 2
6 | 5
The follwing will give me the id and the value of the parent:
select id, left(c.title, instrrev(c.title, "/")-1) as parentValue from nodeIDs
yields
id | parentNode
1 |
2 | /root
3 | /root/x
4 | /root/x/y
5 | /root/x
6 | /root/x/a
What is the extra step needed to return the id's of those parent nodes, rather than their values, i.e, return '1' instead of '/root' in that last table?
Many thanks
Something like this perhaps:
select c.id,
left(c.title, instrrev(c.title, "/")-1) as parentValue
, p.id as parentID
from nodeIDs c
left join
nodeIDs p
on left(c.title, instrrev(c.title, "/")-1) = p.title
Something along these lines, I think.
select t1.id,
left(t1.title, instrrev(t1.title, "/")-1) as parentNode,
t2.id as parentID
from nodeIDs t1
inner join nodeIDs t2 on (left(t1.title, instrrev(t1.title, "/")-1)) = t2.title
I don't have any easy way to test this. But the basic idea is that, having derived the title of the parent node, you can do an inner join on it to get the associated id number.
I have 2 tables that I am trying to combine in a specific way
Table 1: ‘part_defs’ Table 2 Items_part_values
in value_defs:
ID | Name
-------------
1 | color
2 | size
3 | weight
in Items_part_values
ItemID | valueID | Value
-------------------------
10 | 1 | red
11 | 1 | blue
What I need is a query where for a given item all the rows from value_defs appear and if they have a value in Items_part_values the value.
So for Item 11 I want
ID | Name | Value
--------------------
1 | color | red
2 | size | NULL
3 | weight | NULL
I’m new to MySQL, in access I would have created a subquery with the ItemID as a parameter and then done a Left Join with value_defs on the result.
Is there a way of doing something similar in MySQL?
Thanks
Use:
SELECT p.id,
p.name,
ipv.value
FROM PART_DEFS p
LEFT JOIN ITEMS_PART_VALUES ipv ON ipv.valueid = p.id
AND ipv.itemid = ?
Replace the "?" with the itemid you want to search for.
This means all the PARTS_DEF rows will be returned, and if the ITEMS_PART_VALUES.valueid matches the PART_DEFS.id value, then the ITEMS_PART_VALUES.value value will be displayed for the item you are looking for. If there's no match, the value column will be NULL for that record.
There's a difference in OUTER JOINs, when specifying criteria in the JOIN vs the WHERE clause. In the JOIN, the criteria is applied before the JOIN occurs while in the WHERE clause the criteria is applied after the JOIN.
Use a left join:
SELECT * FROM Table1 LEFT JOIN Table2 USING (ID);
Edit:
SELECT * FROM part_defs LEFT JOIN Items_part_values ON part_defs.ID = Items_part_values.valueID;