GoogleSQL for Spanner supports the following syntax to use GQLwithin SQL queries.

Language list

GRAPH_TABLE operator

FROM GRAPH_TABLE (property_graph_namemulti_linear_query_statement) [ [ AS ]alias ]

Description

Performs an operation on a graph in theFROM clause of a SQL query and thenproduces a table with the results.

With theGRAPH_TABLE operator, you can use theGQL syntaxto query a property graph. The result of this operation is produced as a table thatyou 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 forpatterns. For more information, seeGraph query language.
• alias: An optional alias, which you can use to refer to the tableproduced by theGRAPH_TABLE operator elsewhere in the query.

Examples

You can use theRETURN statement to return specific node and edge properties.For example:

SELECTname,idFROMGRAPH_TABLE(FinGraphMATCH(n:Person)RETURNn.nameASname,n.idASid);/*-----------+ | name | id | +-----------+ | Alex | 1  | | Dana | 2  | | Lee  | 3  | +-----------*/

You can use theRETURN statement to produce output with graph patternvariables. These variables can be referenced outsideGRAPH_TABLE. For example,

SELECTn.name,n.idFROMGRAPH_TABLE(FinGraphMATCH(n:Person)RETURNn);/*-----------+ | name | id | +-----------+ | Alex | 1  | | Dana | 2  | | Lee  | 3  | +-----------*/

The following query produces an error becauseid isn'tincluded in theRETURN statement, even though this property exists forelementn:

SELECTname,idFROMGRAPH_TABLE(FinGraphMATCH(n:Person)RETURNn.name);

The following query produces an error because directly outputting the graphelementn is not supported. Convertn to its JSON representation using theSAFE_TO_JSON for successful output.

-- ErrorSELECTnFROMGRAPH_TABLE(FinGraphMATCH(n:Person)RETURNn);

SELECTSAFE_TO_JSON(n)asjson_nodeFROMGRAPH_TABLE(FinGraphMATCH(n:Person)RETURNn);/*---------------------------+ | json_node                 | +---------------------------+ | {"identifier":"mUZpbk...} | | {"identifier":"mUZpbk...} | | {"identifier":"mUZpbk...} | +--------------------------*/