Union

UNION

Similar to C++ std::variant, UNION is a nested data type that is capable of holding multiple alternative values with different types. The value under key “tag” is considered as the value being currently hold by the UNION.

Internally, UNION are implemented as STRUCT with “tag” as one of its keys.

Data Type	DDL definition
UNION	UNION(price FLOAT, note STRING)

Consider the following csv file

1
aa

Example

CREATE NODE TABLE demo(a SERIAL, b UNION(num INT64, str STRING), PRIMARY KEY(a));
COPY demo from "csv file";

MATCH (d:demo) RETURN d.b;
-------
| d.b |
-------
| 1   |
-------
| aa  |
-------

MATCH (d:demo) RETURN union_extract(d.b, 'num');
--------------------------
| UNION_EXTRACT(d.b,num) |
--------------------------
| 1                      |
--------------------------
|                        |
--------------------------

MATCH (d:demo) RETURN union_extract(d.b, 'str');
--------------------------
| UNION_EXTRACT(d.b,str) |
--------------------------
|                        |
--------------------------
| aa                     |
--------------------------

MATCH (d:demo) RETURN union_tag(d.b);
------------------
| UNION_TAG(d.b) |
------------------
| num            |
------------------
| str            |
------------------