S02041
Error Code
S02041
Error Message
The nested joins in a query must return a table. RefId:S02041
Probable Causes
In a JOIN query, if there is a nested join query, the nested query must return a table.
For example, the error will occur if the nested JOIN query uses the EXEC statement and returns a scalar value.
t1 = table(`a as a)
t2 = table(`b as b)
t3 = table(`c as c)
select a from t cross join (exec first(b) from t1 cross join t2)
Solutions
Avoid using the EXEC keyword in the nested JOIN subquery of a JOIN query.