How to merge two sql tables where B is a subset of A and should override A?

Question

Table A (nothing is unique)

╔══════╦══════╦═══════════╦═══════════════╗
║ p_id ║ l_id ║  p_name   ║ p_description ║
╠══════╬══════╬═══════════╬═══════════════╣
║  212 ║    1 ║ Ball      ║ Red           ║
║  212 ║    2 ║ Balle     ║ Rouge         ║
║  301 ║    1 ║ Horn name ║ Blue          ║
╚══════╩══════╩═══════════╩═══════════════╝

Table B (p_id is unique)

╔══════╗
║ p_id ║
╠══════╣
║  101 ║
║  201 ║
║  210 ║
║  212 ║
║  234 ║
║  250 ║
║  301 ║
║  320 ║
╚══════╝

Wrt p_id, Table A is a subset of Table B (all p_id should exist in Table B) but Table A contains different data. Both tables contain a lot more columns that I'm not showing. For table A I'm only concerned with the p_id. For table BI want to eliminate duplicates based on l_id. There will always be an entry with l_id of 1 but there may or may not be others which should be discarded (ie. a simple WHERE l_id=1 should do).

The result should be a table that has every p_id of Table B (once) with every column of Table A. Most of the rows will have no data in those other columns, because they didn't exist in Table B. So I should have this, for example:

╔══════╦══════╦═══════════╦═══════════════╗
║ p_id ║ l_id ║  p_name   ║ p_description ║
╠══════╬══════╬═══════════╬═══════════════╣
║  101 ║      ║           ║               ║
║  201 ║      ║           ║               ║
║  210 ║      ║           ║               ║
║  212 ║    1 ║ Ball      ║ Red           ║
║  234 ║      ║           ║               ║
║  250 ║      ║           ║               ║
║  301 ║    1 ║ Horn name ║ Blue          ║
║  320 ║      ║           ║               ║
╚══════╩══════╩═══════════╩═══════════════╝

Answer 1

From your description, this sounds like a left join :

select b.p_id, a.l_id, a.p_name, a.p_description
from b left join
     a
     on b.p_id = a.p_id and a.l_id = 1;

Answer 2

To get all rows from one table and the rows matching some condition from another you can use a left join :

select b.p_id, a.l_id, a.p_name, a.p_description
from b
left join a on b.p_id = a.p_id and a.l_id = 1

This will get you everything from B with values for the columns in A matching the where condition. For those rows in B that doesn't have any matches you'll get null values.