Select all from Table A, replace values from Table B

Question

So I have this kind of tables:

Lots of values in Tabel A

TABLE_A
ID | TEXT
----------
1  | 'aaa1'  
2  | 'aaa2'
3  | 'aaa3'
4  | 'aaa4'
5  | 'aaa5'
6  | 'aaa6'

Some values in Table B:

TABLE_B
ID | TEXT
----------
4  | 'bbb4'
5  | 'bbb5'

And I want result to give

RESULT
ID | TEXT
----------
1  | 'aaa1'  
2  | 'aaa2'
3  | 'aaa3'
4  | 'bbb4'
5  | 'bbb5'
6  | 'aaa6'

Answer 1

Use a left outer join to join the two tables, and a coalesce() function to select values from table B when they exist.

select  a.id
       ,coalesce(b.text, a.text) as text
from table_a a
left outer join table_b b
  on b.id = a.id