nebula graph踩坑(二)

https://docs.nebula-graph.com.cn/3.0.1/3.ngql-guide/7.general-query-statements/2.match/



CREATE TAG player (name string, age int);
INSERT VERTEX actor(name, age) VALUES "1":("Tim Duncan", 39);
INSERT VERTEX actor(name, age) VALUES "2":("hehe", 32);
INSERT VERTEX actor(name, age) VALUES "3":("haohao", 32);


UPDATE VERTEX ON player "2" SET name = "two"
UPDATE VERTEX ON player "3" SET name = "three"


CREATE TAG INDEX IF NOT EXISTS name ON player(name(20));
CREATE EDGE INDEX IF NOT EXISTS follow_index on follow();

CREATE TAG actor (name string, age int);
INSERT VERTEX actor(name, age) VALUES "player100":("Tim Duncan", 42);

CREATE EDGE IF NOT EXISTS e1();
CREATE EDGE IF NOT EXISTS e2 (name string, age int);


INSERT EDGE e2 (name, age) VALUES "1"->"2":("n1", 12);
INSERT EDGE e2 (name, age) VALUES "3"->"2":("n3", 32);
INSERT EDGE e1 () VALUES "1"->"3":();

INSERT EDGE e1 () VALUES "2"->"3":();
INSERT EDGE e1 () VALUES "3"->"2":();



# 重建索引使其生效。
REBUILD TAG INDEX name;
REBUILD EDGE INDEX follow_index

匹配 Tag
MATCH (v:player) RETURN v  LIMIT 3;

匹配点：
MATCH (v) RETURN v  LIMIT 5;

匹配多tag到点：
MATCH (v:player:actor) RETURN v LIMIT 10;


匹配点的属性
match (v:player{name:"hehe"}) return v
MATCH (v:player) WHERE v.player.name == "Tim Duncan" RETURN v;
MATCH (v)  WHERE id(v) == 'player100'  RETURN v;


点点查找；
match(v:player{name:"hehe"})--(v2) where id(v2) in ["1","2"] return v2;
match (v) return v limit 10

MATCH (v:player{name:"Tim Duncan"})--(v2:player) RETURN v2

用户可以在--符号上增加<或>符号指定边的方向
MATCH (v:player{name:"Tim Duncan"})-->(v2:player)  RETURN v2.player.name AS Name;

case表达式：
MATCH (v:player{name:"Tim Duncan"})--(v2) \
        RETURN \
        CASE WHEN v2.team.name IS NOT NULL \
        THEN v2.team.name  \
        WHEN v2.player.name IS NOT NULL \
        THEN v2.player.name END AS Name;


MATCH (v:player{name:"Tim Duncan"})-->(v2)<--(v3) \
        RETURN v3.player.name AS Name;

匹配路径
MATCH p=(v:player{name:"Tim Duncan"})-->(v2)  RETURN p



匹配边：
MATCH ()<-[e]-() RETURN e LIMIT 3;

匹配边type：
MATCH ()-[e:e1]->()  RETURN e imit 3;
MATCH ()-[e:e2]->()  RETURN e imit 3;


匹配边属性：
MATCH (v:player{name:"Tim Duncan"})-[e:e2{age:12}]->(v2)   RETURN e;


多边type：
MATCH (v:player{name:"Tim Duncan"})-[e:e1|:e2]->(v2) RETURN e;


匹配多边
MATCH (v:player{name:"Tim Duncan"})-[]->(v2)<-[e:e1]-(v3) RETURN v2, v3;


匹配定长路径
MATCH p=(v:player{name:"Tim Duncan"})-[e:e1*2]->(v2)         RETURN DISTINCT v2 AS Friends;
如果hop为 0，模式会匹配路径上的起始点
MATCH (v:player{name:"Tim Duncan"}) -[*0]-> (v2) RETURN v2;

匹配变长路径：

MATCH p=(v:player{name:"Tim Duncan"})-[e:e1*1..3]->(v2) RETURN v2 AS Friends;

匹配多个 Edge type 的变长路径:

MATCH p=(v:player{name:"Tim Duncan"})-[e:e1|e2*2]->(v2)  RETURN DISTINCT v2;


匹配多模式：
MATCH (v1:player{name:"Tim Duncan"}), (v2:actor{name:"Tim Duncan"}) RETURN v1,v2;


多MATCH检索

MATCH (m)-[]->(n) WHERE id(m)=="2" \
        MATCH (n)-[]->(l) WHERE id(n)=="1" \
        RETURN id(m),id(n),id(l);

############
option match


MATCH (m)-[]->(n) WHERE id(m)=="1" RETURN id(m),id(n)

MATCH (m)-[]->(n) WHERE id(m)=="1"  OPTIONAL MATCH (n)-[]->(l) WHERE id(n)=="2"  RETURN id(m),id(n),id(l);


######### lookup

CREATE TAG INDEX IF NOT EXISTS index_player ON player(name(30), age);
REBUILD TAG INDEX index_player;


LOOKUP ON player \
        WHERE player.name == "Tim Duncan" \
        YIELD id(vertex);


LOOKUP ON player WHERE player.age  > 30  IELD id(vertex);


#### 搞挂了 #####
match (v) return v limit 10


LOOKUP ON player \
        WHERE player.name STARTS WITH "h" \
        YIELD properties(vertex).name, properties(vertex).age;





###########
检索边
CREATE EDGE INDEX IF NOT EXISTS index_e2 ON e2(age);
REBUILD EDGE INDEX index_e2;

show jobs;

LOOKUP ON e2  WHERE e2.age == 12 YIELD edge AS e


LOOKUP ON e2 \
        WHERE e2.age > 30 \
        YIELD properties(edge).age;


LOOKUP ON e2 \
        WHERE e2.age == 12 \
        YIELD dst(edge) AS DstVID, properties(edge).age AS age



####### 不好使：
LOOKUP ON e2 \
        WHERE e2.age == 12 \
        YIELD dst(edge) AS DstVID, properties(edge).age AS age |\
        GO FROM $-.DstVID OVER player \
        YIELD $-.DstVID, properties(edge).age, properties($$).name;

############## go #########

GO FROM "1" OVER e2 YIELD dst(edge);

两跳的

GO 2 steps FROM "1" OVER e1 YIELD dst(edge);

过滤条件：

GO FROM "1", "2" OVER e2 \
        WHERE properties(edge).age > 10 \
        YIELD DISTINCT properties($$).name AS team_name, properties(edge).age AS age, properties($^).name AS player_name;


GO FROM "1" OVER e1, e2 YIELD properties(edge).age;

GO FROM "2" OVER e2 REVERSELY \
        YIELD src(edge) AS destination;

该 MATCH 查询与上一个 GO 查询具有相同的语义。
MATCH (v)<-[e:e2]- (v2) WHERE id(v) == '2' \
        RETURN id(v2) AS destination;



GO FROM "2" OVER e2 REVERSELY \
        YIELD src(edge) AS id | \
        GO FROM $-.id OVER e2 \
        WHERE properties($^).age > 10 \
        YIELD properties($^).name AS FriendOf, properties($$).name AS Team;

该 MATCH 查询与上一个 GO 查询具有相同的语义


MATCH (v)-[e:e2]->(v2)<-[e2:e2]-(v3) WHERE id(v) == '1' RETURN v2.player.name AS FriendOf, v3.player.name AS Team;


查询 player100 1~2 跳内的朋友
GO 1 TO 2 STEPS FROM "1" OVER follow \
        YIELD dst(edge) AS destination;

GO 1 TO 2 STEPS FROM "1" OVER e2 YIELD dst(edge) AS destination;
GO 1 TO 2 STEPS FROM "1" OVER e1 YIELD dst(edge) AS destination;


该 MATCH 查询与上一个 GO 查询具有相同的语义。
MATCH (v) -[e:e2*1..2]->(v2) WHERE id(v) == "1" RETURN id(v2) AS destination;

根据年龄分组。
GO 1 STEPS FROM "1" OVER e2 \
        YIELD src(edge) AS src, dst(edge) AS dst, properties($$).age AS age \
        | GROUP BY $-.dst \
        YIELD $-.dst AS dst, collect_set($-.src) AS src, collect($-.age) AS age

分组并限制输出结果的行数。
GO FROM "1" OVER e2 YIELD src(edge) AS src, dst(edge) AS dst;

$a = GO FROM "1" OVER e2 YIELD src(edge) AS src, dst(edge) AS dst; \
        GO  FROM $a.dst OVER e1 \
        YIELD $a.src AS src, $a.dst, src(edge), dst(edge) \
        | ORDER BY $-.src

$a = GO FROM "1" OVER e2 YIELD src(edge) AS src, dst(edge) AS dst; \
        GO  FROM $a.dst OVER e1 \
        YIELD $a.src AS src, $a.dst, src(edge), dst(edge) \
        | ORDER BY $-.src | OFFSET 1 LIMIT 2;


############## fetch 语句：
FETCH PROP ON player "1" YIELD properties(vertex);
FETCH PROP ON player "1" YIELD properties(vertex).name AS name;


多tag上的值：

fetch prop on player,actor "1" yield vertex as v;
fetch prop on player,actor "1","2" yield vertex as v;

FETCH语句中使用*获取当前图空间所有标签里，点的属性值
FETCH PROP ON * "1", "2", "3" YIELD vertex AS v


获取边上的值

FETCH PROP ON e2 "1" -> "2" YIELD properties(edge);
FETCH PROP ON e2 "3" -> "2" YIELD properties(edge);

获取边上的指定属性值：

FETCH PROP ON e2 "1" -> "2"    \
        YIELD properties(edge).age;

获取多条边的属性值：
FETCH PROP ON e2 "1" -> "2", "3" -> "2" YIELD edge AS e;


符合语句：

GO FROM "1" OVER e2 \
        YIELD src(edge) AS s, dst(edge) AS d \
        | FETCH PROP ON e2 $-.s -> $-.d \
        YIELD properties(edge).age;


用户也可以通过自定义变量构建类似的查询。


$var = GO FROM "1" OVER e2 \
        YIELD src(edge) AS s, dst(edge) AS d; \
        FETCH PROP ON e2 $var.s -> $var.d \
        YIELD properties(edge).age;