UPDATE EDGE¶
The UPDATE EDGE statement updates properties on an edge.
In NebulaGraph, UPDATE EDGE supports compare-and-swap (CAS).
Syntax¶
ngql
UPDATE EDGE ON <edge_type>
<src_vid> -> <dst_vid> [@<rank>]
SET <update_prop>
[WHEN <condition>]
[YIELD <output>]
| Parameter | Required | Description | Example |
|---|---|---|---|
ON <edge_type> |
Yes | Specifies the edge type. The properties to be updated must be on this edge type. | ON serve |
<src_vid> |
Yes | Specifies the source vertex ID of the edge. | "player100" |
<dst_vid> |
Yes | Specifies the destination vertex ID of the edge. | "team204" |
<rank> |
No | Specifies the rank of the edge. | 10 |
SET <update_prop> |
Yes | Specifies the properties to be updated and how they will be updated. | SET start_year = start_year +1 |
WHEN <condition> |
No | Specifies the filter conditions. If <condition> evaluates to false, the SET clause does not take effect. |
WHEN end_year < 2010 |
YIELD <output> |
No | Specifies the output format of the statement. | YIELD start_year AS Start_Year |
Example¶
The following example checks the properties of the edge with the GO statement.
ngql
nebula> GO FROM "player100" \
OVER serve \
YIELD properties(edge).start_year, properties(edge).end_year;
+------------------+----------------+
| serve.start_year | serve.end_year |
+------------------+----------------+
| 1997 | 2016 |
+------------------+----------------+
The following example updates the start_year property and returns the end_year and the new start_year.
ngql
nebula> UPDATE EDGE on serve "player100" -> "team204"@0 \
SET start_year = start_year + 1 \
WHEN end_year > 2010 \
YIELD start_year, end_year;
+------------+----------+
| start_year | end_year |
+------------+----------+
| 1998 | 2016 |
+------------+----------+