Cardinality left outer join CDS Part 8 ABAP on HANA Course

Left outer join to many or Left outer joins works:-
Relationship 1:N :- it will create a join even if we don't fetch data from the RHS table
Relationship N:1 l:- it will not create a join if we don't fetch data from the RHS table
1:N and N:1 is the relationship between the LHS table and the RHS table
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Relationship 1:N behaves differently for "Left outer to one join" :-
Select no contain any fields from RHS then optimization takes place join will not form
Aggregate functions like count(*) is used then optimization takes place join will not form
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Code:-
saptechnomania...

[@GauravSingh-lz8mb]

I don't think there is anyone else who can explain this matter as deep as you have done, If someone like is not uderstanding the Cardinality and Joins on data base level please watch carefully Part 8 to Part 12. I am waching it for the second time and enjoying it a lot. thanks a lot.

[@SAPTECHNOMANIAC]

You are right Gourav it might be difficult at first glance but once we understand we never stuck in association in future.

[@bharathreddyk30]

True..

[@ansumanbehera8150]

just one query to ask. at video time 21:51 the SQL trace shows that the join is one to many in native hana trace while the CDS Entity mentioned is left outer to one join vbap as _itm. how both screen showing different things. Kindly clarify.

[@raginitrainings755]

Since we are fetching fields from RHS table (join happend its clear, also if you notice in output we got multiple SO items even though we mentione join to one, becasue when we fetch fieds from RHS, SQL query runs on DB join to many so multiple so items in output, thatsy its shows one-to-many in screen..I think) hope its clear..

[@sree8652]

when you execute the table the results are not refreshed right..how will i solve that problem

[@SAPTECHNOMANIAC]

Clear the console and then execute OR your result will be at the end of the console If you are talking about console result. If table result not updating due to new column addition then re execute the table.

[@123MRPOCO]

if compared one to one join @16:00 and one to many @18:00, still we can see duplicate entries !!. Can you please correct if anythg unnoticed?

[@SAPTECHNOMANIAC]

It's due to I didn't clear console before displaying next result ... It was previous execution data new execution data below the previous execution data ..... When you display the result in console it will not clear existing data in console and just append the result after previous result. what you can see on screen both the time @16:00 and @18:00 both are older execution result . My mistake is that I didn't focus on quesy result showing, I was focusing on to show how join his happening ... According to join only the result will come...

[@diwakarsap]

Hi Ram, Firstly thanks for the explanation!. it was very much helpful for us. One question is incase of N:1 left outer join, join did not happen on VBAK(RHS table). which we saw on the ST05 too, understood. Fundamentally we will get to know that VBAP is an item table, will have either 1 or more entries when compared with VBAK, but how will system get to know that it is an N:1 left outer join only?.

[@SAPTECHNOMANIAC]

Foreign key relationship between these tables

[@bithin14]

Brilliant and deep explanations... Kudos 👌

[@SAPTECHNOMANIAC]

Glad you liked it

[@rajeshsalapu8338]

Good Explanation Sir .Thank you !!!

[@SAPTECHNOMANIAC]

Glad you liked it

[@pavan341210]

thank you for your videos.. very helpful

[@SAPTECHNOMANIAC]

You are welcome!

[@ManojSharma-lr3jh]

Osm video bro 😎.Good job

[@SAPTECHNOMANIAC]

Thank you ...

[@sandeepakumari8582]

nice video'

[@SAPTECHNOMANIAC]

Thanks

[@SathiyaNatarajan-fe6vb]

Nice video

[@SAPTECHNOMANIAC]

Thanks

[@saumyanair8413]

Good content.

[@SAPTECHNOMANIAC]

Appreciated