I have two tables, by joining that 2 tables i need to take distinct count of one particular column from OrientDB. Since joins donot support in OrientDB. Please suggest me in orient db how join works and please suggest me also how to use edges for join in orientdb.
Related
Hi, I have trouble understanding the structure of this table connection.
Let's suppose that all joins are inner join. Does this picture mean:
Orders JOIN (Orders1 JOIN People) JOIN Returns?
or
Orders JOIN Orders1 JOIN (People JOIN Returns)?
I don't understand
Why Orders1 and People are both vertically aligned and both connected with Orders table.
(As my understanding, join operation is bilateral, not trilateral. My imagination is that the joining should be all represented horizontally, looking like a chain.)
I know SQL, it would be easier to explain if write a pseudo SQL script.
The example you have taken is not very good to understand the joins/relationships in tableau.
A wire/line between two tables indicate the join on two tables with some id column (one to many OR one to one OR many to many). You can check the relationship based on which field (read column) by clicking that relationship thread(line). Why I termed this example not a good one because ORDERS table joining itself may have umpteen options. You can edit that relationship in many ways.
So, in you example, ORDERS is joined with itself (ORDERS1). (the result will depend on relationship type of course). Simultaneously ORDERS is joined with PEOPLE table. Since these tables have only one field in common, this relationship has resulted in creation of just one extra column in ORDERS result. NoW PEOPLE is also connected with RETURNS where no column is common so I am not able to understand this relationship.
A watch of this 5 minute video is recommended.
Translating this relationship will be something like..
(ORDERS JOIN (PEOPLE JOIN RETURNS)) JOIN ORDERS1
(Last JOIN outside braces is on the result of braces but with field/fields from ORDERS)
I have an SQL script I want to replicate inside tableau using tableau's joins.
SQL script (script simplified just for explanation):
Select *
From transactions
Inner join data1
UNION
Select *
From transactions
Inner join data2
How do replicate this in tableau using joins n unions? (No tableau custom SQL please)
You can do manual unions or wildcard unions: Tableau Help
Depending on your data connection, some features of it may or may not be supported.
Same with joins, lots of ways to do it: Tableau Help
Make sure you're looking up the docs and searching for an answer before posting. These types of this are easy to find.
I have to write on paper a good physical plan for a Postgresql's query with several natural join, is it the same as treating a query with a simple join or should I use a different approach?
I am working on this one, by the way
SELECT zname
FROM Cage natural join Animal natural join DailyFeeds natural join Zookeeper
WHERE shift=’const’ AND clocation=’const’;
By Oracle
A NATURAL JOIN is a JOIN operation that creates an implicit join
clause for you based on the common columns in the two tables being
joined. Common columns are columns that have the same name in both
tables.
I think the above is answering following
is it the same as treating a query with a simple join or should I use a different approach?
I hope it helps.
I want to know can we write query using two tables ( join) in flink Table and SQL api.
I am new to flik, I want to create two table from two different data set and query them and produce other dataset.
my query would be like select... from table1, table 2... so can we write like this query which querying two tables or more?
Thanks
Flink's Table API supports join operations (full, left, right, inner joins) on batch tables (e.g. those created from a DataSet).
SELECT c, g FROM Table3, Table5 WHERE b = e
For streaming tables (e.g. those created from a DataStream), Flink does not yet support join operations. But the Flink community is actively working to add them in the near future.
I have two very big tables for example tab1 and tab2 in Postgres. I need to perform join and group by operation on these tables, to make my query fast i need indexing. Is there any way how to use index over join and group by queries ?? (as I heard indexing is not possible over join and group by)