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    GQL schema statements

    Graph Query Language (GQL) supports all GoogleSQL DDL statements, including the following GQL-specific DDL statements:

    Statement list

    Name Summary
    CREATE PROPERTY GRAPH statement Creates a property graph.
    DROP PROPERTY GRAPH statement Deletes a property graph.

    CREATE PROPERTY GRAPH statement

    Property graph definition

    CREATE
  [ OR REPLACE ]
  PROPERTY GRAPH
  [ IF NOT EXISTS ] property_graph_name 
 property_graph_content 
; property_graph_content 
: node_tables 
[ edge_tables 
] node_tables 
:
  NODE TABLES element_list 
 edge_tables 
:
  EDGE TABLES element_list 
 element_list 
:
  ( element 
[, ...])

    Description

    Creates a property graph.

    Definitions

    • OR REPLACE : Replaces any property graph with the same name if it exists. If the property graph doesn't exist, creates the property graph. Can't appear with IF NOT EXISTS .
    • IF NOT EXISTS : If any property graph exists with the same name, the CREATE statement has no effect. Can't appear with OR REPLACE .
    • property_graph_name : The name of the property graph. This name can be a path expression. This name must not conflict with the name of an existing table, view, or property graph.
    • property_graph_content : Add the definitions for the nodes and edges in the property graph.

    • node_tables : A collection of node definitions. A node definition defines a new type of node in the graph.

      The following example represents three node definitions: Account , Customer , and GeoLocation .

        NODE 
  
 TABLES 
  
 ( 
  
 Account 
 , 
  
 Customer 
  
 LABEL 
  
 Client 
  
 PROPERTIES 
  
 ( 
 cid 
 , 
  
 name 
 ), 
  
 Location 
  
 AS 
  
 GeoLocation 
  
 DEFAULT 
  
 LABEL 
  
 PROPERTIES 
  
 ALL 
  
 COLUMNS 
 )

    • edge_tables : A collection of edge definitions. An edge definition defines a new type of edge in the graph. An edge is directed and connects a source and a destination node.

      The following example represents two edge definitions: Own and Transfer .

        EDGE 
  
 TABLES 
  
 ( 
  
 Own 
  
 SOURCE 
  
 KEY 
  
 ( 
 cid 
 ) 
  
 REFERENCES 
  
 Customer 
  
 ( 
 cid 
 ) 
  
 DESTINATION 
  
 KEY 
  
 ( 
 aid 
 ) 
  
 REFERENCES 
  
 Account 
  
 NO 
  
 PROPERTIES 
 , 
  
 Transfer 
  
 SOURCE 
  
 KEY 
  
 ( 
 from_id 
 ) 
  
 REFERENCES 
  
 Account 
  
 ( 
 aid 
 ) 
  
 DESTINATION 
  
 KEY 
  
 ( 
 to_id 
 ) 
  
 REFERENCES 
  
 Account 
  
 ( 
 aid 
 ) 
  
 LABEL 
  
 Transfer 
  
 NO 
  
 PROPERTIES 
 )

    • element_list : A list of element (node or edge) definitions.

    • element : Refer to Element definition for details.

    Element definition

     element 
: element_name 
[ AS element_alias 
] element_keys 
[ { label_and_properties_list 
| element_properties 
} ] element_keys 
:
  { node_element_key 
| edge_element_keys 
} node_element_key 
:
  [ element_key 
] edge_element_keys 
:
  [ element_key 
] source_key 
 destination_key 
 element_key 
:
  KEY column_name_list 
 source_key 
:
  SOURCE KEY edge_column_name_list 
REFERENCES element_alias_reference 
[ node_column_name_list 
] destination_key 
:
  DESTINATION KEY edge_column_name_list 
REFERENCES element_alias_reference 
[ node_column_name_list 
] edge_column_name_list 
: column_name_list 
 node_column_name_list 
: column_name_list 
 column_name_list 
:
  ( column_name 
[, ...])

    Description

    Adds an element definition to the property graph. For example:

      Customer 
  
 LABEL 
  
 Client 
  
 PROPERTIES 
  
 ( 
 cid 
 , 
  
 name 
 )

    In a graph, labels and properties are uniquely identified by their names. Labels and properties with the same name can appear in multiple node or edge definitions. However, labels and properties with the same name must follow these rules:

    • Properties with the same name must have the same value type.
    • Labels with the same name must expose the same set of properties.

    Definitions

    • element_name : The name of the input table from which elements are created.
    • element_alias : An optional alias. You must use an alias if you use an input table for more than one element definition.

    • element_keys : The key for a graph element. This uniquely identifies a graph element.

      • By default, the element key is the primary key of the input table.

      • Element keys can be explicitly defined with the KEY clause.

    • node_element_key : The element key for a node.

        KEY 
  
 ( 
 item1_column 
 , 
  
 item2_column 
 )

    • edge_element_keys : The element key, source key, and destination key for an edge.

        KEY 
  
 ( 
 item1_column 
 , 
  
 item2_column 
 ) 
 SOURCE 
  
 KEY 
  
 ( 
 item1_column 
 ) 
  
 REFERENCES 
  
 item_node 
  
 ( 
 item_node_column 
 ) 
 DESTINATION 
  
 KEY 
  
 ( 
 item2_column 
 ) 
  
 REFERENCES 
  
 item_node 
  
 ( 
 item_node_column 
 )

    • element_key : An optional key that identifies the node or edge element. If element_key isn't provided, then the primary key of the table is used.

        KEY 
  
 ( 
 item1_column 
 , 
  
 item2_column 
 )

    • source_key : The key for the source node of the edge.

        SOURCE 
  
 KEY 
  
 ( 
 item1_column 
 ) 
  
 REFERENCES 
  
 item_node 
  
 ( 
 item_node_column 
 )

    • destination_key : The key for the destination node of the edge.

        DESTINATION 
  
 KEY 
  
 ( 
 item2_column 
 ) 
  
 REFERENCES 
  
 item_node 
  
 ( 
 item_node_column 
 )

    • column_name_list : One or more columns to assign to a key.

      In column_name_list , column names must be unique.

    • Reference column name lists:

      • node_column_name_list : One or more columns referenced from the node tables.

      • edge_column_name_list : One or more columns referenced from the edge tables.

      Referenced columns must exist in the corresponding node or edge table.

      If node_column_name_list doesn't exist in source_key or destination_key , then the element_keys of the referenced node are used. In this case, the column order in the element_keys must match the column order in the edge_column_name_list .

    • element_alias_reference : The alias of another element to reference.

    • label_and_properties_list : The list of labels and properties to add to an element. For more information, see Label and properties list definition .

    Label and properties list definition

     label_and_properties_list 
: label_and_properties 
[...] label_and_properties 
: element_label 
[ element_properties 
] element_label 
:
  {
    LABEL label_name 
|
    DEFAULT LABEL
  }

    Description

    Adds a list of labels and properties to an element.

    Definitions

    • label_and_properties : The label to add to the element and the properties exposed by that label. For example:

        LABEL 
  
 Tourist 
  
 PROPERTIES 
  
 ( 
 home_city 
 , 
  
 home_country 
 )

      When label_and_properties isn't specified, the following is applied implicitly:

        DEFAULT 
  
 LABEL 
  
 PROPERTIES 
  
 ARE 
  
 ALL 
  
 COLUMNS

      A property must be unique in label_and_properties .

    • element_label : Add a custom label or use the default label for the element. label_name must be unique in element .

      If you use DEFAULT LABEL , label_name is the same as element_table_alias .

    • element_properties : The properties associated with a label. A property can't be used more than once for a specific label. For more information, see Element properties definition .

    Element properties definition

     element_properties 
:
  {
    NO PROPERTIES | properties_are 
| derived_property_list 
} properties_are 
:
  PROPERTIES [ ARE ] ALL COLUMNS [ EXCEPT column_name_list 
] column_name_list 
:
  ( column_name 
[, ...]) derived_property_list 
:
  PROPERTIES ( derived_property 
[, ...]) derived_property 
: value_expression 
[ AS property_name 
]

    Description

    Adds properties associated with a label.

    Definitions

    • NO PROPERTIES : The element doesn't have properties.

    • properties_are : Define which columns to include as element properties.

      If you don't include this definition, all columns are included by default, and the following definition is applied implicitly:

        PROPERTIES 
  
 ARE 
  
 ALL 
  
 COLUMNS

      In the following examples, all columns in a table are included as element properties:

        PROPERTIES 
  
 ARE 
  
 ALL 
  
 COLUMNS 
 

        PROPERTIES 
  
 ALL 
  
 COLUMNS

      In the following example, all columns in a table except for home_city and home_country are included as element properties:

        PROPERTIES 
  
 ARE 
  
 ALL 
  
 COLUMNS 
  
 EXCEPT 
  
 ( 
 home_city 
 , 
  
 home_country 
 )

    • column_name_list : A list of columns to exclude as element properties.

      Column names in the EXCEPT column_name_list must be unique.

    • derived_property_list : A list of element property definitions.

    • derived_property : An expression that defines a property and can optionally reference the input table columns.

      In the following example, the id and name columns are included as properties. Additionally, the result of the salary + bonus expression are included as the income property:

        PROPERTIES 
  
 ( 
 id 
 , 
  
 name 
 , 
  
 salary 
  
 + 
  
 bonus 
  
 AS 
  
 income 
 )

      A derived property includes:

      • value_expression : An expression that can be represented by simple constructs such as column references and functions. Subqueries are excluded.

      • AS property_name : Alias to assign to the value expression. This is optional unless value_expression is a function.

      If derived_property has any column reference in value_expression , that column reference must refer to a column of the underlying table.

      If derived_property doesn't define property_name , value_expression must be a column reference and the implicit property_name is the column name.

    FinGraph example

    To create a property graph, you must first create tables that describe the nodes and edges. Run the following statements to create and populate a dataset called graph_db with tables that describe people, financial accounts that they own, and transfers between accounts:

      CREATE 
  
 SCHEMA 
  
 IF 
  
 NOT 
  
 EXISTS 
  
 graph_db 
 ; 
 CREATE 
  
 OR 
  
 REPLACE 
  
 TABLE 
  
 graph_db 
 . 
 Person 
  
 ( 
  
 id 
  
 INT64 
 , 
  
 name 
  
 STRING 
 , 
  
 birthday 
  
 TIMESTAMP 
 , 
  
 country 
  
 STRING 
 , 
  
 city 
  
 STRING 
 , 
  
 PRIMARY 
  
 KEY 
  
 ( 
 id 
 ) 
  
 NOT 
  
 ENFORCED 
 ); 
 CREATE 
  
 OR 
  
 REPLACE 
  
 TABLE 
  
 graph_db 
 . 
 Account 
  
 ( 
  
 id 
  
 INT64 
 , 
  
 create_time 
  
 TIMESTAMP 
 , 
  
 is_blocked 
  
 BOOL 
 , 
  
 nick_name 
  
 STRING 
 , 
  
 PRIMARY 
  
 KEY 
  
 ( 
 id 
 ) 
  
 NOT 
  
 ENFORCED 
 ); 
 CREATE 
  
 OR 
  
 REPLACE 
  
 TABLE 
  
 graph_db 
 . 
 PersonOwnAccount 
  
 ( 
  
 id 
  
 INT64 
  
 NOT 
  
 NULL 
 , 
  
 account_id 
  
 INT64 
  
 NOT 
  
 NULL 
 , 
  
 create_time 
  
 TIMESTAMP 
 , 
  
 PRIMARY 
  
 KEY 
  
 ( 
 id 
 , 
  
 account_id 
 ) 
  
 NOT 
  
 ENFORCED 
 , 
  
 FOREIGN 
  
 KEY 
  
 ( 
 id 
 ) 
  
 REFERENCES 
  
 graph_db 
 . 
 Person 
 ( 
 id 
 ) 
  
 NOT 
  
 ENFORCED 
 , 
  
 FOREIGN 
  
 KEY 
  
 ( 
 account_id 
 ) 
  
 REFERENCES 
  
 graph_db 
 . 
 Account 
 ( 
 id 
 ) 
  
 NOT 
  
 ENFORCED 
 ); 
 CREATE 
  
 OR 
  
 REPLACE 
  
 TABLE 
  
 graph_db 
 . 
 AccountTransferAccount 
  
 ( 
  
 id 
  
 INT64 
  
 NOT 
  
 NULL 
 , 
  
 to_id 
  
 INT64 
  
 NOT 
  
 NULL 
 , 
  
 amount 
  
 FLOAT64 
 , 
  
 create_time 
  
 TIMESTAMP 
  
 NOT 
  
 NULL 
 , 
  
 order_number 
  
 STRING 
 , 
  
 PRIMARY 
  
 KEY 
  
 ( 
 id 
 , 
  
 to_id 
 , 
  
 create_time 
 ) 
  
 NOT 
  
 ENFORCED 
 , 
  
 FOREIGN 
  
 KEY 
  
 ( 
 id 
 ) 
  
 REFERENCES 
  
 graph_db 
 . 
 Account 
 ( 
 id 
 ) 
  
 NOT 
  
 ENFORCED 
 , 
  
 FOREIGN 
  
 KEY 
  
 ( 
 to_id 
 ) 
  
 REFERENCES 
  
 graph_db 
 . 
 Account 
 ( 
 id 
 ) 
  
 NOT 
  
 ENFORCED 
 );

    Next, run the following statements to insert data into each of the tables that you created:

      INSERT 
  
 INTO 
  
 graph_db 
 . 
 Account 
  
 ( 
 id 
 , 
  
 create_time 
 , 
  
 is_blocked 
 , 
  
 nick_name 
 ) 
 VALUES 
  
 ( 
 7 
 , 
 "2020-01-10 06:22:20.222" 
 , 
 false 
 , 
 "Vacation Fund" 
 ), 
  
 ( 
 16 
 , 
 "2020-01-27 17:55:09.206" 
 , 
 true 
 , 
 "Vacation Fund" 
 ), 
  
 ( 
 20 
 , 
 "2020-02-18 05:44:20.655" 
 , 
 false 
 , 
 "Rainy Day Fund" 
 ); 
 INSERT 
  
 INTO 
  
 graph_db 
 . 
 Person 
  
 ( 
 id 
 , 
  
 name 
 , 
  
 birthday 
 , 
  
 country 
 , 
  
 city 
 ) 
 VALUES 
  
 ( 
 1 
 , 
 "Alex" 
 , 
 "1991-12-21 00:00:00" 
 , 
 "Australia" 
 , 
 "Adelaide" 
 ), 
  
 ( 
 2 
 , 
 "Dana" 
 , 
 "1980-10-31 00:00:00" 
 , 
 "Czech_Republic" 
 , 
 "Moravia" 
 ), 
  
 ( 
 3 
 , 
 "Lee" 
 , 
 "1986-12-07 00:00:00" 
 , 
 "India" 
 , 
 "Kollam" 
 ); 
 INSERT 
  
 INTO 
  
 graph_db 
 . 
 AccountTransferAccount 
  
 ( 
 id 
 , 
  
 to_id 
 , 
  
 amount 
 , 
  
 create_time 
 , 
  
 order_number 
 ) 
 VALUES 
  
 ( 
 7 
 , 
 16 
 , 
 300 
 , 
 "2020-08-29 15:28:58.647" 
 , 
 "304330008004315" 
 ), 
  
 ( 
 7 
 , 
 16 
 , 
 100 
 , 
 "2020-10-04 16:55:05.342" 
 , 
 "304120005529714" 
 ), 
  
 ( 
 16 
 , 
 20 
 , 
 300 
 , 
 "2020-09-25 02:36:14.926" 
 , 
 "103650009791820" 
 ), 
  
 ( 
 20 
 , 
 7 
 , 
 500 
 , 
 "2020-10-04 16:55:05.342" 
 , 
 "304120005529714" 
 ), 
  
 ( 
 20 
 , 
 16 
 , 
 200 
 , 
 "2020-10-17 03:59:40.247" 
 , 
 "302290001255747" 
 ); 
 INSERT 
  
 INTO 
  
 graph_db 
 . 
 PersonOwnAccount 
  
 ( 
 id 
 , 
  
 account_id 
 , 
  
 create_time 
 ) 
 VALUES 
  
 ( 
 1 
 , 
 7 
 , 
 "2020-01-10 06:22:20.222" 
 ), 
  
 ( 
 2 
 , 
 20 
 , 
 "2020-01-27 17:55:09.206" 
 ), 
  
 ( 
 3 
 , 
 16 
 , 
 "2020-02-18 05:44:20.655" 
 );

    The following property graph, FinGraph , contains two node definitions ( Account and Person ) and two edge definitions ( PersonOwnAccount and AccountTransferAccount ).

      CREATE 
  
 OR 
  
 REPLACE 
  
 PROPERTY 
  
 GRAPH 
  
 graph_db 
 . 
 FinGraph 
  
 NODE 
  
 TABLES 
  
 ( 
  
 graph_db 
 . 
 Account 
 , 
  
 graph_db 
 . 
 Person 
  
 ) 
  
 EDGE 
  
 TABLES 
  
 ( 
  
 graph_db 
 . 
 PersonOwnAccount 
  
 SOURCE 
  
 KEY 
  
 ( 
 id 
 ) 
  
 REFERENCES 
  
 Person 
  
 ( 
 id 
 ) 
  
 DESTINATION 
  
 KEY 
  
 ( 
 account_id 
 ) 
  
 REFERENCES 
  
 Account 
  
 ( 
 id 
 ) 
  
 LABEL 
  
 Owns 
 , 
  
 graph_db 
 . 
 AccountTransferAccount 
  
 SOURCE 
  
 KEY 
  
 ( 
 id 
 ) 
  
 REFERENCES 
  
 Account 
  
 ( 
 id 
 ) 
  
 DESTINATION 
  
 KEY 
  
 ( 
 to_id 
 ) 
  
 REFERENCES 
  
 Account 
  
 ( 
 id 
 ) 
  
 LABEL 
  
 Transfers 
  
 );

    Visualization of financial graph example

    Once the property graph is created, you can use it in GQL queries. For example, the following query matches all nodes labeled Person and then returns the name values in the results.

      GRAPH 
  
 graph_db 
 . 
 FinGraph 
 MATCH 
  
 ( 
 p 
 : 
 Person 
 ) 
 RETURN 
  
 p 
 . 
 name 
 /*---------+ 
 | name    | 
 +---------+ 
 | Alex    | 
 | Dana    | 
 | Lee     | 
 +---------*/

    DROP PROPERTY GRAPH statement

    DROP PROPERTY GRAPH [ IF EXISTS ] property_graph_name 
;

    Description

    Deletes a property graph.

    Definitions

    • IF EXISTS : If a property graph of the specified name doesn't exist, then the DROP statement has no effect and no error is generated.
    • property_graph_name : The name of the property graph to drop.

    Example

      DROP 
  
 PROPERTY 
  
 GRAPH 
  
 graph_db 
 . 
 FinGraph 
 ;
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