Which Join should I use when connecting 2 tables

[walkerist]

Table PAPERVERSIONS

Table PAPERAUTHORS

I was trying to get the display the Paper Author but not familiar with SELECT JOIN on ABAP

Expected output is to dispaly Schmee Maluche

Here's my code:

SELECT SINGLE paperversions~paper_id, paperauthors~paper_id<br>  

FROM paperversion<br>    

INNER JOIN paperauthors<br>     

ON paperversions~paper_id = paperauthors~paper_id<br>  

INTO  @l_test<br>  

WHERE paper_author EQ  @ "MY CUSTOM FIELD XXX"

[Sandra_Rossi]

Why do you use WHERE paper_author = ... if the author is what you're looking for.

Do you mean WHERE paper_id = ... ? (and then you should have SELECT paper_author...)

Please clarify...

[walkerist]

sandra.rossi apologies for the confusion. I would like to display the paper_author

[Sandra_Rossi]

I guess the current answers solve your question, please mark one as accepted or vote accordingly.

[anujawani2426 · Accepted solution]

Hi,

Please try below code. Below query will display paper id and corresponding paper author. if you just want to print paper author then write only paper_author in select single.

SELECT SINGLE paperversions~paper_id, paperauthors~paper_author  

FROM paperversions    

INNER JOIN paperauthors     

ON paperversions~paper_id = paperauthors~paper_id  

INTO  @l_test  

WHERE paper_author EQ  @ "MY CUSTOM FIELD XXX"

Regards,

Anuja Kawadiwale

[walkerist · Accepted solution]

Hello this is my current code but the paper_author doesn't appear.

SELECT SINGLE paper_author  

FROM paperversions    

INNER JOIN paperauthors     

ON paperversions~paper_id = paperauthors~paper_id  

INTO  @l_test  

WHERE paper_author EQ  @ "MY CUSTOM FIELD XXX"

[anujawani2426 · Accepted solution]

Hi,

If you want to print only paper_autor which is present in paperauthors table then you don't need to join both tables.

You can directly fetch paper_author from paperauthors table.

SELECT SINGLE paper_author  

FROM paperauthors     

INTO  @l_test  

WHERE paper_author EQ  @ "MY CUSTOM FIELD XXX"

[venkateswaran_k]

Hi

If you use INNER JOIN - then both the tables should have that ID (you passed in where clause) - else no rows will be displayed

If you use LEFT OUTER JOIN - then the table on left side you used, it will display all rows that matches the id that you pass in where clause ( even if auther table does not contain that id)