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add annotation to some examples of OPTIONAL MATCH clause #2396

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Dec 21, 2023
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add annotation to some examples of OPTIONAL MATCH clause #2396

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2 changes: 2 additions & 0 deletions docs-2.0-zh/3.ngql-guide/7.general-query-statements/optional-match.md
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@
`MATCH`语句中使用`OPTIONAL MATCH`的示例如下：

```ngql
# 找出特定节点 m（ID为 "player100" 的节点）直接连接的节点，以及这些节点 n 直连的下一层节点 l (OPTIONAL MATCH (n)-[]->(l))， 如果没有找到这样的节点 l，查询也会继续， l 的返回值是 null。
nebula> MATCH (m)-[]->(n) WHERE id(m)=="player100" \
OPTIONAL MATCH (n)-[]->(l) \
RETURN id(m),id(n),id(l);
Expand All @@ -39,6 +40,7 @@ nebula> MATCH (m)-[]->(n) WHERE id(m)=="player100" \
而使用多`MATCH`，不使用`OPTIONAL MATCH`时，会返回模式完全匹配的行。示例如下：

```ngql
# 找出特定节点 m（ID为 "player100" 的节点）直接连接的节点，以及这些节点 n 直连的下一层节点 l, 节点 l 必须存在。
nebula> MATCH (m)-[]->(n) WHERE id(m)=="player100" \
MATCH (n)-[]->(l) \
RETURN id(m),id(n),id(l);
Expand Down