I would like to compare two columns, A and B.
If Col A and Col B share the same value, I would like Col A to have a no value set. If Col A and Col B do not share the same value, I would like Col A to keep the original value it has.
Below is what I attempted. However, it returns "true" for all entries in the case column - Col A (corrected).
select *,
case when 'Col A' = 'Col B'
then 'Col A' = null
else 'Col A' = 'Col A'
end as "Col A (corrected)"
from my_table
select
case
when col_a=col_b then null
else col_a
end as col_a_corrected
from my_table
Simply do
select *,
NULLIF(col_a, col_b)
from my_table
The NULLIF
returns null if col_a = col_b, otherwise col_a is returned.
https://www.postgresql.org/docs/current/functions-conditional.html#FUNCTIONS-NULLIF
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