I am using two sub queries with CALL statements. There are different matches and conditions applied in each sub query. if first sub query not producing any results then am not getting the result in the second call statement.
My syntax is like below.
MATCH (n:Person) WHERE n.id = 'CID0001'
CALL
{
WITH n
MATCH (n) - [: .....] -> ()
WHERE .....
MATCH (n) - [: ....] -> (p)
RETURN p
LIMIT 1
}
CALL
{
WITH n
MATCH (n) <- [: .....] - ()
WHERE .....
MATCH (n) <- [: ....] - (c)
RETURN c
LIMIT 1
}
WITH n, coalesce(p,c) as subvalue
RETURN n, subvalue
LIMIT 20
If first call statement fails then i am not getting the result in second call. I know the sub query will works like this. I changed the MATCH as OPTIONAL MATCH in each sub query like below.
MATCH (n:Person) WHERE n.id = 'CID0001'
CALL
{
WITH n
OPTIONAL MATCH (n) - [: .....] -> ()
WHERE .....
OPTIONAL MATCH (n) - [: ....] -> (p)
RETURN p
LIMIT 1
}
CALL
{
WITH n
OPTIONAL MATCH (n) <- [: .....] - ()
WHERE .....
OPTIONAL MATCH (n) <- [: ....] - (c)
RETURN c
LIMIT 1
}
WITH n, coalesce(p,c) as subvalue
where (p is not null or c is not null)
RETURN n, subvalue
LIMIT 20
I am getting results but am facing another issue. When using OPTIONAL MATCH, I am getting null values from sub queries. Since we are limiting the results to one record inside sub query, NULL is returned even though subsequent records having not null values. Is there any alternative way to achieve this without using OPTIONAL MATCH statements.