Sorry for vague question title.
I've got a table containing huge list of, say, products, belonging to different categories. There's a foreign key column indicating which category that particular product belongs to. I.e. in "bananas" row category might be 3 which indicates "fruits".
Now I added additional column "order" which is for display order within that particular category. I need to do initial ordering. Since the list is big, I dont wanna change every row by hand. Is it possible to do with one or two queries? I dont care what initial order is as long as it starts with 1 and goes up.
I cant do something like SET order = id because id counts from 1 up regardless of product category and order must start anew from 1 up for every different category.
Example of what I need to achieve:
ID | product | category | Order
1 | bananas | fruits | 1
2 | chair | furniture | 1
3 | apples | fruits | 2
4 | cola | drinks | 1
5 | mango | fruits | 3
6 | pepsi | drinks | 2
(category is actually a number because it's foreign key, in example I put names just for clarification)
As you see, order numbers start anew from 1 for each different category.
Sounds like something a SQL procedure would be handy for.
Why not just set the order to the category? That is, why not:
update Table
set SortOrder = Category;
As an aside, you cannot have a column named order -- that is a reserved word in SQL.
Related
I have two tables. Table A & Table B. Table A has 40516 rows, and records sales by seller_id. The first column in Table A is the seller_id that repeats every time a sale is made.
Example: Table A (40516 rows)
seller_id | item | cost
------------------------
1 | dog | 5000
1 | cat | 50
4 |lizard| 80
5 |bird | 20
5 |fish | 90
The seller_id is also present in Table B, and also contains the corresponding name of the seller.
Example: Table B (5851 rows)
seller_id | seller_name
-------------------------
1 | Dog and Cat World INC
4 | Reptile Love.com
5 | Ocean Dogs Inc
I want to join these two tables, but only display the seller name from Table B and all other columns from Table A. When I do this with an INNER JOIN I get 40864 rows (348 extra rows). Shouldn't the query produce only the original 40516 rows?
Also not sure if this matters, but the seller_id can contain several zeros before the number (e.g., 0000845, 0000549).
I've looked around on here and haven't really found an answer. I've tried LEFT and RIGHT joins and get the same results for one and way more results for the other.
SQL Code Example:
SELECT public.table_B.seller_name, *
FROM public.table_A
INNER JOIN public.table_B ON public.table_A.seller_id =
public.table_B.seller_id;
Expected Results:
seller_name | seller_id | item | cost
------------------------------------------------
Dog and Cat World INC | 1 | dog | 5000
Dog and Cat World INC | 1 | cat | 50
Reptile Love.com | 4 |lizard| 80
Ocean Dogs Inc | 5 |bird | 20
Ocean Dogs Inc | 5 |fish | 90
I expected the results to contain the same number of rows in Table A. Instead I gut names matching up and an additional 348 rows...
Update:
I changed "unique_id" to "seller_id" in the question.
I guess I should have chosen a better name for unique_id in the original example. I didn't mean it to be unique in the sense of a key. It is just the seller's id that repeats every time there is a sale (in Table A). The seller's ID does repeat in Table A because it is supposed to. I simply want to pair up the seller IDs with the seller names.
Thanks again everyone for their help!
unique_id is already not correctly named in the first table, so there is no reason to assume it is unique in the second table either.
Run this query to find the duplicates:
select unique_id
from table_b
group by unique_id
having count(*) > 1;
You can fix the query using distinct on:
SELECT b.seller_name, a.*
FROM public.table_A a JOIN
(SELECT DISTINCT ON (b.unique_id) b.*
FROM public.table_B b
ORDER BY b.unique_id
) b
ON a.unique_id = b.unique_id;
In this case, you may get fewer records, if there are no matches. To fix that, use a LEFT JOIN.
Because unique id column is not unique.
Gordon Linoff was correct. The seller_id (formerly listed as unique_id) was indeed duplicated throughout the data set. I foolishly assumed otherwise. Also the seller_name had many duplicates too! In the end I had to use the CONCAT() function to join the seller_id with second identifier to create a type of foreign key. After I did this the join worked as expected. Thanks everyone!
I have 2 different databases. They track different things about inventory. in essence they share 3 common fields. Location, item number and quantity. I've extracted these into 2 tables, with only those fields. Every time I find an answer, it doesn't get all the test cases, just some of the fields.
Items can be in multiple locations, and as a turn each location can have multiple items. The primary key would be location and item number.
I need to flag when an entry doesn't match all three fields.
I've only been able to find queries that match an ID or so, or who's queries are beyond my comprehension. in the below, I'd need a query that would show that rows 1,2, and 5 had issues. I'd run it on each table and have to verify it with a physical inventory.
Please refrain from commenting on it being silly having information in 2 different databases, All I get in response it to deal with it =P
Table A
Location ItemNum | QTY
-------------------------
1a1a | as1001 | 5
1a1b | as1003 | 10
1a1b | as1004 | 2
1a1c | as1005 | 15
1a1d | as1005 | 15
Table B
Location ItemNum | QTY
-------------------------
1a1a | as1001 | 10
1a1d | as1003 | 10
1a1b | as1004 | 2
1a1c | as1005 | 15
1a1e | as1005 | 15
This article seemed to do what I wanted but I couldn't get it to work.
To find entries in Table A that don't have an exactly matching entry in Table B:
select A.*
from A
left join B on A.location = B.location and A.ItemNum = B.ItemNum and A.qty = B.qty
where B.location Is Null
Just swap all the A's and B's to get the list of entries in B with no matching entry in A.
I have an issue. Suppose i have the table in Northwind database, where there are orders placed containing some products.
Order | Product
1 | Milk
1 | Cacao
1 | Juice
2 | Milk
2 | LemonJuice
2 | OrangeJuice
3 | Lemonade
3 | Remoulade
3 | GrapefruitJuice
Suppose Order is being placed and it contains FX Order 1 Milk, Cacao, Juice. Order 2 has Milk, LemonJuice, OrangeJuice.
I need to select all the orders which contains Milk ordered and to select the rest what have they ordered, SO If person in order 1 has ordered Milk, then i need to take cacao and juice as well. The same in order 2, I see Milk ordered, then i need to take LemonJuice and OrangeJuice, Whereas Order 3 does not contain Milk, So I do not need it.
How can i do that?
Trying for the second day, I am really in doubt of how to write it..
An embedded select would do it:
Select * from Orders where ord in
(select ord from Orders where Product = "Milk");
One thing I would like to point out is that "Order" is a keyword in SQLite, so you cannot name your column "Order". As you see in my code-snippet I renamed it to "ord". (The Table is called Orders and the second column is called (as in your description) Product.
I have trouble with a complex ordering problem. I have following example data:
table "categories"
id | frequency
1 | 0
2 | 4
3 | 0
table "entries"
id | category_id | type
1 | 1 | a
2 | 1 | a
3 | 1 | a
4 | 2 | b
5 | 2 | c
6 | 3 | d
I want to put entries rows in an order so that category_id,
and type are distributed evenly.
More precisely, I want to order entries in a way that:
category_ids that refer to a category that has frequency=0 are
distributed evenly - so that a row is followed by a different category_id
whenever possible. e.g. category_ids of rows: 1,2,1,3,1,2.
Rows with category_ids of categories with frequency<>0 should
be inserted from ca. the beginning with a minimum of frequency rows between them
(the gaps should vary). In my example these are rows with category_id=2.
So the result could start with row id #1, then #4, then a minimum of 4 rows of other
categories, then #5.
in the end result rows with same type should not be next to each other.
Example result:
id | category_id | type
1 | 1 | a
4 | 2 | b
2 | 1 | a
6 | 3 | d
.. some other row ..
.. some other row ..
.. some other row ..
5 | 2 | c
entries are like a stream of things the user gets (one at a time).
The whole ordering should give users some variation. It's just there to not
present them similar entries all the time, so it doesn't have to be perfect.
The query also does not have to give the same result on each call - using
random() is totally fine.
frequencies are there to give entries of certain categories a higher
priority so that they are not distributed across the whole range, but are placed more
at the beginning of the result list. Even if there are a lot of these entries, they
should not completely crowd out the frequency=0 entries at the beginning, through.
I'm no sure how to start this. I think I can use window functions and
ntile() to distribute rows by category_id and type.
But I have no idea how to insert the non-0-category-entries afterwards.
I have this random table with random contents.
id | name| mission
1 | aaaa | kitr
2 | bbbb | etre
3 | ccccc| qwqw
4 | dddd | qwert
5 | eeee | potentials
6 | ffffffff | toto
What I want is to add in the above table a column with id=3 with different name and different mission BUT the OLD id =3 I want to have an id = 4 with the name and the mission that it had before when it was id=3, and the OLD id =4 become id=5 with the name and mission of id 5 and so on.
its like i want to enter a column inside of the columns and the below column i want to increase there id +1 but the columns rest the same. example below:
id | name| mission
1 | aaaa | kitr
2 | bbbb | etre
3 | zzzzzz| zzzzz
4 | ccccc| qwqw
5 | dddd | qwert
6 | eeee | potentials
7 | ffffffff | toto
why I want to do this ? I have a table that has 2 CLOB. Inside of those CLOBS there are different queries ex: id =1 has clob of creation of a table id=2 inserts for the columns id=3 has creation of another table id=4 has functions
if you add all of this id in one text(or clob) they will have to create then inserts then create then functions. that table it is like a huge script .
Why I am doing this ? The developers are building their application and they want the sql to work in specific order and I have 6 developers and am organizing the data modeling and the performance and how the scripts are running .So the above table is to organize the calling of the scripts that they wany
Simply put, don't do it.
This case highlights why you should never use any business value, i.e. any 'real world values' for a Primary Key.
In your case I would recommend primary keys not be used for any other purposes.
I recommend you add an extra column 'order' and then change THAT column in order to re-order the rows. That way your primary key and all the other records will not need to be touched.
This avoid the issue that your approach would need to change ALL the database records below the current record which seems like a really bad approach. Just imagine trying to undo that update ;)
Some more info here: https://stackoverflow.com/a/8777574/631619
UPDATE random_table r1
SET id =
(SELECT CASE WHEN id > 2 THEN id+1 ELSE id END id FROM random_table r2
WHERE r1.mission=r2.mission
)
Then insert the new value.