Druid SQL join case

does druid does not support it? (even using nvl)

my simple query is as follow:

select * from A
left join B on A.col =
case when B.col is null then A.col
else A.col

or using nvl

select * from A
left join B on A.col = nvl(B.col, A.col)

thanks

sorry, first query supposed to be:

select * from A
left join B on A.col =
case when B.col is null then A.col
else B.col

Is the “case” condition necessary - isn’t this just what a left (vs inner) join does?

Joins have support for limited cases - eg, joining to a lookup table. For more details about joins,
see https://druid.apache.org/docs/latest/querying/datasource.html#join, and for a bit more,
https://druid.apache.org/docs/latest/querying/joins.html and https://imply.io/post/apache-druid-joins.