NULL¶

You can set the properties for vertices or edges to NULL. Also, you can set NOT NULL constraint to make sure that the property values are NOT NULL.

If not specified, the property is set to NULL by default.

Logical operations with NULL¶

The logical operations with NULL is the same as openCypher.

Here is the truth table for AND, OR, XOR, and NOT.

OpenCypher compatibility¶

The comparisons and operations about NULL are different from openCypher.

The behavior may change later.

Comparisons with NULL¶

The comparison operations with NULL is incompatible with openCypher.

Operations and expression with NULL¶

The NULL operations and RETURN with NULL is incompatible with openCypher.

Examples¶

Create a tag named player. Specify the property name with NOT NULL. Ignore the property age constraint.

nebula> CREATE TAG player(name string NOT NULL, age int);
Execution succeeded (time spent 5001/5980 us)

The property name is NOT NULL. The property age is NULL by default.

nebula> SHOW CREATE TAG player;
+-----------+-----------------------------------+
| Tag       | Create Tag                        |
+-----------+-----------------------------------+
| "student" | "CREATE TAG `player` (           |
|           |  `name` string NOT NULL,          |
|           |  `age` int64 NULL                 |
|           | ) ttl_duration = 0, ttl_col = """ |
+-----------+-----------------------------------+

nebula> INSERT VERTEX player(name, age) VALUES "Kobe":("Kobe",null);
Execution succeeded (time spent 6367/7357 us)