Union

UNION is the clause where you combine query result A and query result B that have the same schema but were produced by different queries into a single result C by taking their union. Two notes:

• The number of columns and dataType of each column must be identical in A and B but their names can be different.
• UNION will remove all duplicates in the union of A and B. Instead, UNION ALL preserves the duplicates.

We will use the example database for demonstration, whose schema and data import commands are given here.

For example, the following query returns the age of the follower of Zhang and Karissa without duplicate elimination:

MATCH (u1:User)-[:Follows]->(u2:User)
WHERE u2.name = 'Zhang'
RETURN u1.age
UNION ALL
MATCH (u3:User)-[:Follows]->(u4:User)
WHERE u4.name = 'Karissa'
RETURN u3.age;

Result:

----------
| u1.age |
----------
| 30     |
----------
| 40     |
----------
| 30     |
----------

If you changed UNION ALL to UNION in the above query, one of the 30’s in the output would be removed. So the result would be:

------
| 30 |
------
| 40 |
------