collect 函数¶
collect()函数返回一个符合表达式返回结果的列表。该函数可以将多条记录或值合并进一个列表，实现数据聚合。
collect()是一个聚合函数，类似 SQL 中的GROUP BY。
示例¶
nebula> UNWIND [1, 2, 1] AS a \
RETURN a;
+---+
| a |
+---+
| 1 |
| 2 |
| 1 |
+---+
nebula> UNWIND [1, 2, 1] AS a \
RETURN collect(a);
+------------+
| collect(a) |
+------------+
| [1, 2, 1] |
+------------+
nebula> UNWIND [1, 2, 1] AS a \
RETURN a, collect(a), size(collect(a));
+---+------------+------------------+
| a | collect(a) | size(collect(a)) |
+---+------------+------------------+
| 2 | [2] | 1 |
| 1 | [1, 1] | 2 |
+---+------------+------------------+
# 降序排列，限制输出行数为 3，然后将结果输出到列表中。
nebula> UNWIND ["c", "b", "a", "d" ] AS p \
WITH p AS q \
ORDER BY q DESC LIMIT 3 \
RETURN collect(q);
+-----------------+
| collect(q) |
+-----------------+
| ["d", "c", "b"] |
+-----------------+
nebula> WITH [1, 1, 2, 2] AS coll \
UNWIND coll AS x \
WITH DISTINCT x \
RETURN collect(x) AS ss;
+--------+
| ss |
+--------+
| [1, 2] |
+--------+
nebula> MATCH (n:player) \
RETURN collect(n.age);
+---------------------------------------------------------------+
| collect(n.age) |
+---------------------------------------------------------------+
| [32, 32, 34, 29, 41, 40, 33, 25, 40, 37, ...
...
# 基于年龄聚合姓名。
nebula> MATCH (n:player) \
RETURN n.age AS age, collect(n.name);
+-----+--------------------------------------------------------------------------+
| age | collect(n.name) |
+-----+--------------------------------------------------------------------------+
| 24 | ["Giannis Antetokounmpo"] |
| 20 | ["Luka Doncic"] |
| 25 | ["Joel Embiid", "Kyle Anderson"] |
+-----+--------------------------------------------------------------------------+
...
最后更新:
March 7, 2023