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Sets

The set is a composite data type. A set is a set of values. Unlike a List, values in a set are unordered and each value must be unique.

A set starts with a left curly bracket { and ends with a right curly bracket }. A set contains zero, one, or more expressions. Set elements are separated from each other with commas (,). Whitespace around elements is ignored in the set, thus line breaks, tab stops, and blanks can be used for formatting.

OpenCypher compatibility

  • A composite data type (i.e. set, map, and list) CANNOT be stored as properties of vertices or edges.
  • A set is not a data type in openCypher, but in nGQL, users can use the set.

Examples

# The following query returns the set {1,2,3}.
nebula> RETURN set{1, 2, 3} AS a;
+-----------+
| a         |
+-----------+
| {3, 2, 1} |
+-----------+

# The following query returns the set {1,2}, Because the set does not allow repeating elements, and the order is unordered.
nebula> RETURN set{1, 2, 1} AS a;
+--------+
| a      |
+--------+
| {2, 1} |
+--------+

# The following query checks whether the set has the specified element 1.
nebula> RETURN 1 IN set{1, 2} AS a;
+------+
| a    |
+------+
| true |
+------+

# The following query counts the number of elements in the set.
nebula> YIELD size(set{1, 2, 1}) AS a;
+---+
| a |
+---+
| 2 |
+---+

# The following query returns a set of target vertex property values.
nebula> GO FROM "player100" OVER follow \
        YIELD set{properties($$).name,properties($$).age} as a;
+-----------------------+
| a                     |
+-----------------------+
| {36, "Tony Parker"}   |
| {41, "Manu Ginobili"} |
+-----------------------+
Last update: January 14, 2022
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