comments

docs-2.0/3.ngql-guide/1.nGQL-overview/comments.md

@@ -0,0 +1,46 @@
+# Comments
+
+This topic will describe the comments in nGQL.
+
+## Legacy version compatibility
+
+* In Nebula Graph 1.0, four comment styles: `#`, `--`, `//`, `/* */`.
+* In Nebula Graph 2.0, `--` represents [an edge pattern](../../3.ngql-guide/1.nGQL-overview/3.graph-patterns.md) and cannot be used as comments.
+
+## Examples
+
+```ngql
+nebula> # Do nothing in this line
+nebula> RETURN 1+1;     # This comment continues to the end of this line.
+nebula> RETURN 1+1;     // This comment continues to the end of this line.
+nebula> RETURN 1 /* This is an in-line comment. */ + 1 == 2;
+nebula> RETURN 11 +            \
+/* Multi-line comment.       \
+Use a backslash as a line break.   \
+*/ 12;
+```
+
+In nGQL statement, the backslash `\` in a line indicates a line break.
+
+## OpenCypher compatibility
+
+* In nGQL, you must add a `\` at the end of every line, even in multi-line comments `/* */`.
+* In openCypher, there is no need to use a `\` as a line break.
+
+```openCypher
+/* openCypher style:
+The following comment
+spans more than
+one line */
+MATCH (n:label)
+RETURN n;
+```
+
+```ngql
+/* nGQL style:  \
+The following comment       \
+spans more than     \
+one line */       \
+MATCH (n:tag) \
+RETURN n;
+```

mkdocs.yml

@@ -67,6 +67,7 @@ nav:
       - nGQL overview:
         - Overview: 3.ngql-guide/1.nGQL-overview/1.overview.md
         - Graph patterns: 3.ngql-guide/1.nGQL-overview/3.graph-patterns.md
+        - Comments: 3.ngql-guide/1.nGQL-overview/comments.md
       - Data types:
         - Numeric: 3.ngql-guide/3.data-types/1.numeric.md
         - Boolean: 3.ngql-guide/3.data-types/2.boolean.md