WITH¶
The WITH clause can retrieve the output from a query part, process it, and pass it to the next query part as the input.
OpenCypher compatibility¶
This topic applies to openCypher syntax only.
Note
WITH has a similar function with the Pipe symbol in native nGQL, but they work in different ways. DO NOT use pipe symbols in the openCypher syntax or use WITH in native nGQL statements.
Combine statements and form a composite query¶
Use a WITH clause to combine statements and transfer the output of a statement as the input of another statement.
Example 1¶
The following statement:
- Matches a path.
- Outputs all the vertices on the path to a list with the
nodes()function. - Unwinds the list into rows.
- Removes duplicated vertices and returns a set of distinct vertices.
nebula> MATCH p=(v:player{name:"Tim Duncan"})--() \
WITH nodes(p) AS n \
UNWIND n AS n1 \
RETURN DISTINCT n1;
+-----------------------------------------------------------+
| n1 |
+-----------------------------------------------------------+
| ("player100" :player{age: 42, name: "Tim Duncan"}) |
| ("player101" :player{age: 36, name: "Tony Parker"}) |
| ("team204" :team{name: "Spurs"}) |
| ("player102" :player{age: 33, name: "LaMarcus Aldridge"}) |
| ("player125" :player{age: 41, name: "Manu Ginobili"}) |
| ("player104" :player{age: 32, name: "Marco Belinelli"}) |
| ("player144" :player{age: 47, name: "Shaquille O'Neal"}) |
| ("player105" :player{age: 31, name: "Danny Green"}) |
| ("player113" :player{age: 29, name: "Dejounte Murray"}) |
| ("player107" :player{age: 32, name: "Aron Baynes"}) |
| ("player109" :player{age: 34, name: "Tiago Splitter"}) |
| ("player108" :player{age: 36, name: "Boris Diaw"}) |
+-----------------------------------------------------------+
Example 2¶
The following statement:
- Matches the vertex with the VID
player100. - Outputs all the tags of the vertex into a list with the
labels()function. - Unwinds the list into rows.
- Returns the output.
nebula> MATCH (v) \
WHERE id(v)=="player100" \
WITH labels(v) AS tags_unf \
UNWIND tags_unf AS tags_f \
RETURN tags_f;
+----------+
| tags_f |
+----------+
| "star" |
| "player" |
| "person" |
+----------+
Filter composite queries¶
WITH can work as a filter in the middle of a composite query.
nebula> MATCH (v:player)-->(v2:player) \
WITH DISTINCT v2 AS v2, v2.age AS Age \
ORDER BY Age \
WHERE Age<25 \
RETURN v2.name AS Name, Age;
+----------------------+-----+
| Name | Age |
+----------------------+-----+
| "Luka Doncic" | 20 |
| "Ben Simmons" | 22 |
| "Kristaps Porzingis" | 23 |
+----------------------+-----+
Process the output before using collect()¶
Use a WITH clause to sort and limit the output before using collect() to transform the output into a list.
nebula> MATCH (v:player) \
WITH v.name AS Name \
ORDER BY Name DESC \
LIMIT 3 \
RETURN collect(Name);
+-----------------------------------------------+
| collect(Name) |
+-----------------------------------------------+
| ["Yao Ming", "Vince Carter", "Tracy McGrady"] |
+-----------------------------------------------+
Use with RETURN¶
Set an alias using a WITH clause, and then output the result through a RETURN clause.
nebula> WITH [1, 2, 3] AS list RETURN 3 IN list AS r;
+------+
| r |
+------+
| true |
+------+
nebula> WITH 4 AS one, 3 AS two RETURN one > two AS result;
+--------+
| result |
+--------+
| true |
+--------+