In my viz I have 2 tables, Orders and Returns
I have created a column called Order Id using Custom Split for Returns Table.
Now I'm trying to join the Orders and returns table using the Order Id but Order Id doesn't show up in the join drop down. how do i go about from here to create a custom join calculation option.
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When you split a column, it shows up as a "Calculated field". If you want to join on something which is not in the primary data source then you might as well create it first and then load the data in Tableau.
You must have noticed though that the split columns show up when you move to a worksheet. In your case, you can simply join on the "Order ID" which is present in both data sets (Superstore data).
Hope this helps.
Related
I would like to organize my postgresql table in ascending order from the date it was created on.
So I tried:
SELECT *
FROM price
ORDER BY created_on;
And it did show me the database in that order, however it did not save it.
Is there a way I can make it so it gets saved?
Tables in a relational database represent unordered sets. There is no such thing as the "order of rows" in a table.
If you need a specific sort order, the only way is to use an order by in a select statement as you did.
If you don't want to type the order by each time, you can create a view that does that:
create view sorted_price
as
select *
from price
order by created_on;
But be warned: if you sort the rows from the view in a different way, e.g. select * from sorted_price order by created_on desc Postgres will actually apply two sorts. The query optimizer is unfortunately not smart enough to remove the one store in the view's definition.
I'm completely new to SQL and have a question. I am using is PostgreSQL.
I have two tables called "employees" and "offices"
The table "employees" have a list of unique employees with each having an OfficeID (The office where they work).
What I want to do is to "count" the number of appearances of the Office_ID and take that count into the table "offices" where the "office_ID" have a column called "number_of_employees".
Being completely new to SQL the only thing I have managed to even come close to this is fore example.
SELECT COUNT(*)
FROM employees
WHERE office_id = 203
But this only selects and gives the sum of rows with the id "203" that has to be manually entered into "number of empolyees"
What I want is a trigger function that updates the field "number_of_empolyees" when a new record is inserted into the table "empolyees"
A view is the way to go here.
I am assuming since you're completely new to SQL, you're unsure how to make it work (Edit: just seen your comment after posting :^D) .
The correct way to count employees for each office is:
SELECT office_id, COUNT(*) as employeeCount
FROM employees
GROUP BY office_id
Note how your WHERE office_id = XXX has been replaced by a GROUP BY office_id in order to count employees for all offices in a single query.
That being done, we can use it inside the view.
Be careful about the JOIN: I believe in your schema, an office may have no employee (for instance, right after you created it or right before you delete it). We will handle that part with a LEFT JOIN.
CREATE VIEW OfficeWithEmployeeCount AS
SELECT Offices.*, EmployeeCount
FROM Offices
LEFT OUTER JOIN (SELECT office_id, COUNT(*) as EmployeeCount FROM Employees GROUP BY office_id) T
ON Offices.office_id = T.office_id
Note: to avoid having NULL returned in EmployeeCount for empty offices, you may want to write:
CREATE VIEW OfficeWithEmployeeCount AS
SELECT Offices.*, COALESCE(EmployeeCount,0)
FROM ...
I'm trying to build a request to get the data from a table, but some of those columns have foreign keys I would like to replace by the associated keyword in one request.
Basically there's
table A with column 1:PKA-ID and column 2:name.
table B with column 1:PKB-ID, column 2:FKA-ID, column 3:amount.
I want to get all the lines in table B but with all foreign keys replaced by the associated names in table A.
I started building a request with a subrequest + alias to get that, but ofc I have more than one result per subrequest, yet I can't find a way to link that subrequest to the ID of table B [might be exhausted, dumb or both] from the main request. I did something like that:
SELECT (SELECT "NAME" FROM A JOIN B ON ID = FKA-ID) AS name, amount FROM TABLEB;
it feels so simple of a request yet...
You don't need a join in the subselect.
SELECT pkb_id,
(SELECT name FROM a WHERE a.pka_id = b.fka_id),
amount
FROM b;
(See it live in SQL Fiddle).
The subselect query runs for each and every row of its parent select and has the parent row available from the context.
You can also use a simple join.
SELECT b.pkb_id, a.name, b.amount
FROM b, a
WHERE a.pka_id = b.fka_id;
Note that the join version puts less restrictions on the PostgreSQL query optimizer so in some cases the join version might work faster. (For example, in PostgreSQL 9.6 the join might utilize multiple CPU units, cf. Parallel Query).
I have a table that contains Customer No_ and Amount on each row. I want to write a report that shows total amount by customer, by salesperson. I can inner join another table to get the salesperson. Just can't figure out the Customer No_ and Amount query.
I think you can just add sum(i.Amount) to your select and also to your group by. (Sorry, I don't have access to SQL Server at the moment to test this.)
I am developing a t-sql query to return left join of two tables, but when I just select records from Table A, it gives me only 2 records. The problem though is when I left join it Table B, it gives me 4 records. How can I reduce this to just 2 records?
One problem though is that I am only aware of one PK/FK to link these two tables.
The field you are using for the join must exist more than once in table B - this is why multiple rows are being returned in the join. In order to reduce the row count you will have to either add further fields to the join, or add a where clause to filter out rows not required.
Alternatively you could use a GROUP BY statement to group the rows up, but this may not be what you need.
Remember that the left join brings you null fields from joined table.
Also you can use select(distinct), but i can't see well you issue. Can you give us more details?