Newbie with databases, I would like some advise please..
I have agencies who can download photo's.
Standard each agency can download "medium" & "large" photos.
Now from their account page I would like them to make extra custom presets and manage those.
I looked in the database of some blog software how they handle categories and wrapped my head around this example. Is this the right approach?
Cheers
agency 1 has preset "medium" & "large"
agency 2 has preset "medium", "large" & "Bill custom"
-----------
| presets |
-----------------------------------------------
| preset_id | preset_name | preset_dimensions |
-----------------------------------------------
| 1 | medium | 800x600 |
| 2 | large | 3000x2000 |
| 3 | Bill custom | 640x420 |
-----------------------------------------------
----------------
| preset_assoc |
------------------------------------------------------------
| presassoc_id | presassoc_preset_id | presassoc_agency_id |
------------------------------------------------------------
| 1 | 1 | 1 |
| 2 | 2 | 1 |
| 3 | 1 | 2 |
| 4 | 2 | 2 |
| 5 | 3 | 2 |
------------------------------------------------------------
------------
| agencies |
---------------------------
| agency_id | agency_name |
---------------------------
| 1 | Joe ltd |
| 2 | Bill inc |
---------------------------
The approach is right. Because you have NxN relation (1 agency can have multiple presets, and the same preset could be used by multiple agencies) you need to have a joining table. The only questionable thing is that preset_assoc doesn't have to have presassoc_id because the other 2 columns could be used as a combined primary key.
Related
What is the best way for storing enumerated fields with ability to change its order?
Lets say my database looks like this:
| Table |
|---------------------|
| id | name | order|
| 1 | 1st | 1 |
| 2 | 2nd | 2 |
| 3 | 3rd | 3 |
| 4 | 4th | 4 |
Now, when user change order in such a away
| Table |
|---------------------|
| id | name | order|
| 1 | 1st | 1 |
| 4 | 4nd | 2 |
| 2 | 2nd | 3 |
| 3 | 3rd | 4 |
Here I would have to update all rows in this table.
I consider 2 solutions
Solution 1)
When inserting row X between for example order 2 and order 3, I would change row's X order field to 3.5, So I would choose number in the middle between adjacent orders.
Above table would look like this
| Table |
|---------------------|
| id | name | order|
| 1 | 1st | 1 |
| 4 | 4nd | 2.5 |
| 2 | 2nd | 2 |
| 3 | 3rd | 3 |
Then, after for example 16 changes I would update table and normalize all order fields, so table after normalization would be like this:
| Table |
|---------------------|
| id | name | order|
| 1 | 1st | 1 |
| 4 | 4nd | 2 |
| 2 | 2nd | 3 |
| 3 | 3rd | 4 |
Solution 2)
I also consider adding fields "next" (or "next" and "prev") to each row, but it looks for me like waste of memory.
I really dont want to update whole table every time somebody change order. What is the best way of solving this problem?
Basically I'm trying to figure out how Amazon architected their book section. Check out Amazon's book page here (https://www.amazon.com/s/ref=lp_2_ex_n_1?rh=n%3A283155&bbn=283155&ie=UTF8&qid=1522817105).
We are given several main categories: Arts & Photography, Biographies & Memoirs, etc.
If I click on Biographies & Memoirs for example, I'm lead to a series of sub categories. I.E. Biographies & Memoirs > Historical > Asia > Japan
There are repeating sub-category names for example: History > Asia > Japan
How can I map this kind of information so that it is scalable?
Below is the wrong way to do it...?
Categories table
+----+-----------------------+-----------+
| id | name | parent_id |
+----+-----------------------+-----------+
| 1 | Biographies & Memoirs | null |
| 2 | Historical | 1 |
| 3 | Asia | 2 |
| 4 | History | null |
| 5 | Asia | 4 |
| 6 | Japan | 5 |
| 7 | Japan | 3 |
+----+-----------------------+-----------+
Books
+----+-------------------------------------+----------+
| id | name | category |
+----+-------------------------------------+----------+
| 1 | The Lone Samurai | 7 |
| 2 | The Human Tradition in Modern Japan | 7 |
| 3 | Okinawa: The Last Battle | 6 |
+----+-------------------------------------+----------+
Authors
+----+---------------+----------+
| id | firstname | lastname |
+----+---------------+----------+
| 1 | James M. | Burns |
| 2 | Roy E. | Appleman |
| 3 | Russell A. | Gugeler |
| 4 | John | Stevens |
| 5 | William Scott | Wilson |
| 6 | Anne | Walthall |
+----+---------------+----------+
Authors to books (Many to many)
+---------+-----------+
| book_id | author_id |
+---------+-----------+
| 3 | 1 |
| 3 | 2 |
| 3 | 3 |
| 3 | 4 |
| 1 | 5 |
| 2 | 6 |
+---------+-----------+
I was wondering if you can help me with the following problem in spss syntax.
My dataset has nested structure.
Data are nested in companies, then each company has 1 or 2 bosses, but in this case I care only about boss 1. At a previous stage in time the boss graded the workers (not all of them). Now, the ID and the grade of the workers is on the row each worker.
I would like to move the information that was obtained during worker's assessment and create new sets of variables for each (worker ID and grade) on the line/row of the boss.
+---------+------+--------+--------------+---------+---------+--------+---------+
| company | boss |workerID|worker's grade|N:workID1|N:grade1 |N:work2 |N:grade2 |
+---------+------+--------+--------------+---------+---------+--------+---------+
| A | 1 | 1 | | 3 | A | 4 | A |
| A | 2 | 2 | | | |
| A | 0 | 3 | A | | |
| A | 0 | 4 | A | | |
| A | 0 | 5 | | | |
| B | 1 | 1 | | 3 | B | 4 | A |
| B | 0 | 2 | | | |
| B | 0 | 3 | B | | |
| B | 0 | 4 | A | | |
| C | 1 | 1 | | 2 | D | -1 | -1 |
| C | 0 | 2 | D | | |
I would like to move the worker's id and the grade that to the row of the boss in the NEW variables, without loosing the existing variables on workerID and worker's grade.
Basically, I will need to feed forward the information into the new variables and to the row of boss EQ 1 separately for each company.
I have no idea how to proceed with this. I assume that I need a loop that creates new variable for each worker ID that has a valid grade and then feeds forward the information from the worker's row to the boss' newly generated variables.
Any suggestions are very wellcome :-)
Take a look at VARSTOCASES (Data > Restructure)
I am having a logic issue in relation to querying an SQL database. I need to exclude 3 different categories and any item that is included in those categories; however, if an item under one of those categories meets the criteria for another category I need to keep said item.
This is an example output I will get after querying the database at its current version:
ExampleDB | item_num | pro_type | area | description
1 | 45KX-76Y | FLCM | Finished | coil8x
2 | 68WO-93H | FLCL | Similar | y45Kx
3 | 05RH-27N | FLDR | Finished | KH72n
4 | 84OH-95W | FLEP | Final | tar5x
5 | 81RS-67F | FLEP | Final | tar7x
6 | 48YU-40Q | FLCM | Final | bile6
7 | 19VB-89S | FLDR | Warranty | exp380
8 | 76CS-01U | FLCL | Gator | low5
9 | 28OC-08Z | FLCM | Redo | coil34Y
item_num and description are in a table together, and pro_type and area are in 2 separate tables--a total of 3 tables to pull data from.
I need to construct a query that will not pull back any item_num where area is equal to: Finished, Final, and Redo; but I also need to pull in any item_num that meets the type criteria: FLCM and FLEP. In the end my query should look like this:
ExampleDB | item_num | pro_type | area | description
1 | 45KX-76Y | FLCM | Finished | coil8x
2 | 68WO-93H | FLCL | Similar | y45Kx
3 | 84OH-95W | FLEP | Final | tar5x
4 | 81RS-67F | FLEP | Final | tar7x
5 | 19VB-89S | FLDR | Warranty | exp380
6 | 76CS-01U | FLCL | Gator | low5
7 | 28OC-08Z | FLCM | Redo | coil34Y
Try this:
select * from table
join...
where area not in('finished', 'final', 'redo') or type in('flcm', 'flep')
Are you looking for something like
SELECT *
FROM Table_1
JOIN Table_ProType ON Table_1.whatnot = Table_ProType.whatnot
JOIN Table_Area ON Table_1.whatnot = Table_Area.whatnot
WHERE Table.area NOT IN ('Finished','Final','Redo') OR ProType.pro_type IN ('FLCM','FLEP')
Giving the names of the three tables and the joining criteria will help me improve the answer.
I have "components" which can be assembled in different ways into a "system". I want my database to hold all these "components", their type specific data and define how they are connected to each other to form a "system".
The systems are typically gearboxes and they can have rather complex branched designs. Let's start with an easy example:
This system is built up out of Masses (horizontal lines) and Stiffnesses (vertical lines). Gears and clutches are types of masses and come in pairs. Colors represent different branch speeds due to gear ratios. Here's a (bad) example of how I could store everything from this particular illustration:
ID | Type | Clutch | Ends | DrivenBy | NoOfTeeth| Mass | Stiffness
--- | ---- | ------ | ---- | --------- | -------- | ---- | ---------
1 | Mass | | Input1 | | | 5 |
2 | Stiffness | | | | | | 15
3 | Mass | 1.1 | | | | 2 |
4 | Mass | 1.2 | | | | 3 |
5 | Stiffness | | | | | | 20
6 | Gear | | | | 10 | 4 |
7 | Stiffness | | | | | | 30
8 | Gear | | | | 4 | 5 |
9 | Gear | | | 8 | 7 | 2 |
10 | Stiffness | | | | | | 40
11 | Mass | | | | | 4 |
12 | Stiffness | | Output1 | | | | 10
13 | Gear | | | 6 | 5 | 4 |
14 | Stiffness | | | | | | 20
15 | Mass | 2.1 | | | | 4 |
16 | Mass | 2.2 | | | | 3
17 | Stiffness | | | | | | 30
18 | Mass | | Output2 | | | 2 |
Obviously, this is not a very good way to store the data. This design pattern resembles somewhat of a "Repeated attributes" since each component type has a different attribute to be filled. I could create a table for each type of component, but things become more complex when looking at other examples, such as this 2-stage gearbox:
There are also examples with more than 1 input and several outputs, but I can't post more links due to low reputation.
Eitherway, you will see that the usual hierarchical data storage doesn't apply here because the data is not purely "tree-shaped" where everything branches off from 1 main branch.
I think that even though I could store data in the above mentioned way, I will get huge difficulties when it comes to the programming stage.
To add to the complexity, these gearboxes are actually sub-systems to a much bigger system.
So, any suggestions on a good way to store this type of data?*
Perhaps this is a possible way of doing it?
Here you will see that there is a "main" table called GearboxBranch, keeping track of all elements in the gearbox, giving them an id and to identify in which branch the element exists.
Then for the elements themselves, masses are defined in their dedicated table, so are stiffnesses. Gears and Clutches (which are types of masses) are then defined in their perspective tables. A recursive relationship is existing in the gear table, since one gear has to be driven by at least one other gear.
Furthermore, the table with Shaft Ends defines which of the elements in the gearbox are input or output and what number they have.
I can't seem to see any problems with this method, but I'm a little unsure how to get data out of the database. There will be considerable coding involved I'm afraid.