GoogleSQL for Spanner supports the following syntax to use GQL within SQL queries.
Language list
| Name | Summary |
|---|---|
GRAPH_TABLE
operator
|
Performs an operation on a graph in the FROM
clause of a SQL
query and then produces a table with the results. |
GRAPH_TABLE
operator
FROM GRAPH_TABLE ( property_graph_name multi_linear_query_statement ) [ [ AS ] alias ]
Description
Performs an operation on a graph in the FROM
clause of a SQL query and then
produces a table with the results.
With the GRAPH_TABLE
operator, you can use the GQL syntax
to query a property graph. The result of this operation is produced as a table that
you can use in the rest of the query.
Definitions
-
property_graph_name: The name of the property graph to query for patterns. -
multi_linear_query_statement: You can use GQL to query a property graph for patterns. For more information, see Graph query language . -
alias: An optional alias, which you can use to refer to the table produced by theGRAPH_TABLEoperator elsewhere in the query.
Examples
You can use the RETURN
statement to return specific node and edge properties.
For example:
SELECT
name
,
id
FROM
GRAPH_TABLE
(
FinGraph
MATCH
(
n
:
Person
)
RETURN
n
.
name
AS
name
,
n
.
id
AS
id
);
/*-----------+
| name | id |
+-----------+
| Alex | 1 |
| Dana | 2 |
| Lee | 3 |
+-----------*/
You can use the RETURN
statement to produce output with graph pattern
variables. These variables can be referenced outside GRAPH_TABLE
. For example,
SELECT
n
.
name
,
n
.
id
FROM
GRAPH_TABLE
(
FinGraph
MATCH
(
n
:
Person
)
RETURN
n
);
/*-----------+
| name | id |
+-----------+
| Alex | 1 |
| Dana | 2 |
| Lee | 3 |
+-----------*/
The following query produces an error because id
isn't
included in the RETURN
statement, even though this property exists for
element n
:
SELECT
name
,
id
FROM
GRAPH_TABLE
(
FinGraph
MATCH
(
n
:
Person
)
RETURN
n
.
name
);
The following query produces an error because directly outputting the graph
element n
is not supported. Convert n
to its JSON representation using the SAFE_TO_JSON
for successful output.
-- Error
SELECT
n
FROM
GRAPH_TABLE
(
FinGraph
MATCH
(
n
:
Person
)
RETURN
n
);
SELECT
SAFE_TO_JSON
(
n
)
as
json_node
FROM
GRAPH_TABLE
(
FinGraph
MATCH
(
n
:
Person
)
RETURN
n
);
/*---------------------------+
| json_node |
+---------------------------+
| {"identifier":"mUZpbk...} |
| {"identifier":"mUZpbk...} |
| {"identifier":"mUZpbk...} |
+--------------------------*/
