{"id":1291,"date":"2024-08-25T10:45:33","date_gmt":"2024-08-25T02:45:33","guid":{"rendered":"https:\/\/www.fanyamin.com\/wordpress\/?p=1291"},"modified":"2024-08-25T22:41:39","modified_gmt":"2024-08-25T14:41:39","slug":"%e7%94%a8-cypher-%e6%9d%a5%e6%9f%a5%e8%af%a2%e5%9b%be%e6%95%b0%e6%8d%ae%e5%ba%93","status":"publish","type":"post","link":"https:\/\/www.fanyamin.com\/wordpress\/?p=1291","title":{"rendered":"\u7528 Cypher \u6765\u67e5\u8be2\u56fe\u6570\u636e\u5e93"},"content":{"rendered":"

Cyper<\/h1>\n

\u4f5c\u4e3a\u58f0\u660e\u5f0f\u67e5\u8be2\u8bed\u8a00, SQL \u5728\u8ba1\u7b97\u673a\u884c\u4e1a\u65e0\u4eba\u4e0d\u6653, \u65e0\u4eba\u4e0d\u77e5. \u800c Cypher<\/strong> \u5c31\u662f Graph Database \u56fe\u6570\u636e\u5e93\u7684 SQL.<\/p>\n

\n

Cypher is unique because it provides a visual way of matching patterns and relationships.<\/p>\n

Cypher was inspired by an ASCII-art type of syntax where (nodes)-[:ARE_CONNECTED_TO]->(otherNodes)<\/code> using rounded brackets for circular (nodes)<\/code>, and -[:ARROWS]-><\/code> for relationships. <\/p>\n<\/blockquote>\n

Cypher \u7528"\u5706\u62ec\u53f7"\u6765\u8868\u793a\u8282\u70b9, \u7528"\u65b9\u62ec\u53f7,\u8fde\u63a5\u7ebf\u53ca\u7bad\u5934"\u8868\u793a\u5173\u7cfb<\/p>\n

\n

When you write a query, you draw a graph pattern through your data.<\/p>\n<\/blockquote>\n

\u8fd9\u6837\u4e00\u53e5\u8bdd - "Sally likes Graphs. Sally is friends with John. Sally works for Neo4j." \u8868\u793a\u4e3a\u56fe\u6570\u636e\u5e93\u4e2d\u7684\u8282\u70b9\u548c\u5173\u7cfb<\/p>\n

\"file\"<\/p>\n

\u5982\u4f55\u8868\u793a\u8282\u70b9<\/h2>\n

\u5706\u62ec\u53f7\u8868\u793a\u8282\u70b9, \u5176\u4e2d\u8282\u70b9\u7684\u6807\u7b7e label \u53ef\u4ee5\u7528 "node:label" \u6765\u8868\u793a
\n\u4f8b\u5982:<\/p>\n

()                  \/\/anonymous node (no label or variable) can refer to any node in the database\n(p:Person)          \/\/using variable p and label Person\n(:Technology)       \/\/no variable, label Technology\n(work:Company)      \/\/using variable work and label Company<\/code><\/pre>\n
\u5982\u4f55\u8868\u793a\u5173\u7cfb<\/h2>\n
\u6709\u5411\u56fe\u4e2d\u7684\u5173\u7cfb\u5c31\u662f\u7528\u7bad\u5934\u6765\u8868\u793a\u7684, Cypher \u4f7f\u7528\u7bad\u5934  --><\/code> \u6216  <--<\/code> \u6765\u8fde\u63a5\u4e24\u4e2a\u8282\u70b9.
\n\u800c\u6ca1\u6709\u7bad\u5934\u7684\u8fde\u63a5\u7ebf --<\/code> \u8868\u793a\u8282\u70b9\u4e4b\u95f4\u7684\u5173\u7cfb\u662f\u53cc\u5411\u7684<\/p>\n
\u521b\u5efa\u548c\u67e5\u8be2 "Person" \u4e0e "Technology" \u4e4b\u95f4\u5173\u7cfb\u7684\u8bed\u53e5\u5982\u4e0b<\/p>\n
\/\/data stored with this direction \u521b\u5efa\u5173\u7cfb\nCREATE (p:Person)-[:LIKES]->(t:Technology)\n\n\/\/query relationship backwards will not return results \u67e5\u8be2\u5173\u7cfb\nMATCH (p:Person)<-[:LIKES]-(t:Technology)\n\n\/\/better to query with undirected relationship unless sure of direction\nMATCH (p:Person)-[:LIKES]-(t:Technology)<\/code><\/pre>\n
Relationship types<\/h2>\n
\u5173\u7cfb\u7c7b\u578b\u53ef\u4ee5\u81ea\u5df1\u5b9a\u4e49, \u63a8\u8350\u4f7f\u7528\u52a8\u8bcd (verbs and actions)
\n\u4f8b\u5982\u4ee5\u4e0b\u7684\u5173\u7cfb\u7c7b\u578b<\/p>\n
# \u838e\u8389\u559c\u6b22\u56fe\n[:LIKES] - makes sense when we put nodes on either side of the relationship (Sally LIKES Graphs)  \n\n#  \u838e\u8389\u4e3a neo4j \u5de5\u4f5c\n[:IS_FRIENDS_WITH] - makes sense when we put nodes with it (Sally IS_FRIENDS_WITH John)  \n\n# \u838e\u8389\u4e3a neo4j \u5de5\u4f5c\n[:WORKS_FOR] - makes sense with nodes (Sally WORKS_FOR Neo4j)\n<\/code><\/pre>\n
Relationship variables<\/h2>\n
\u4e3a\u67e5\u8be2\u65b9\u4fbf, \u53ef\u4ee5\u7ed9\u5173\u7cfb\u547d\u540d\u4e00\u4e2a\u53d8\u91cf, \u5f62\u5982 [r]<\/code> \u6216 [rel]<\/code><\/p>\n
Node or relationship properties<\/h2>\n
\u8282\u70b9\u548c\u5173\u7cfb\u7684\u5c5e\u6027\u90fd\u53ef\u5728\u8282\u70b9\u7684\u62ec\u53f7\u6216\u5173\u7cfb\u7684\u62ec\u53f7\u5185\u4f7f\u7528\u82b1\u62ec\u53f7\u3002\u7136\u540e\uff0c\u5c5e\u6027\u7684\u540d\u79f0\u548c\u503c\u653e\u5728\u82b1\u62ec\u53f7\u5185\u3002<\/p>\n
\u4f8b\u5982<\/p>\n
# \u8282\u70b9\u5c5e\u6027: p \u662f\u8282\u70b9\u540d, Person \u662f\u6807\u7b7e, \u5c5e\u6027\u540d\u662f name, \u5c5e\u6027\u503c\u662f Sally\nNode property: (p:Person {name: 'Sally'})\n\n# \u5173\u7cfb\u5c5e\u6027: rel \u662f\u5c5e\u6027\u540d, IS_FRIENDS_WITH \u662f\u6807\u7b7e, \u5c5e\u6027\u540d\u662f since, \u5c5e\u6027\u503c\u662f 2018\nRelationship property: -[rel:IS_FRIENDS_WITH {since: 2018}]-><\/code><\/pre>\n
\"file\"<\/p>\n
Patterns in Cypher<\/h2>\n
\u5728 Cypher \u4e2d\u7684\u6a21\u5f0f\u53ef\u80fd\u901a\u8fc7\u4ee5\u4e0a\u7684\u8282\u70b9, \u5173\u7cfb\u548c\u5c5e\u6027\u653e\u5728\u4e00\u8d77\u6765\u8868\u793a, \u4ee5\u9017\u53f7\u5206\u9694.<\/p>\n
\u4f8b\u5982\u6211\u4eec\u8981\u67e5\u8be2\u6a21\u5f0f "Sally likes Graph", \u53ef\u4ee5\u8fd9\u6837\u8868\u793a<\/p>\n
(p:Person {name: "Sally"})-[rel:LIKES]->(g:Technology {type: "Graphs"})<\/code><\/pre>\n
Practice<\/h2>\n