Connecting an Oracle database
You can use an Oracle database as a data source for your GraphQL API by extending your
GraphQL API with the @dbquery
directive.
Any Query
or Mutation
field in your GraphQL schema can be
annotated with the @dbquery
directive to connect to a database backend.
@dbquery (type: String!, schema: String!, query: String, table: String, configuration: String!)
For more information on the @dbquery
directive, see Directives.
Use the arguments in the following sections when you want to connect to an Oracle database as a data source for your GraphQL API.
type
Required. This argument specifies the type of database to query. Supported values are
mysql
, postgresql
, mssql
, trino
,
presto
, singlestore
, db2
,
oracle
, and snowflake
.
schema
Required. This argument specifies the schema of database to query.
table
Optional. The value of this argument is the name of the database table to be queried. While this
value is optional, one of either table
or query
must be
specified.
Using the table
argument is the equivalent of writing select * from
[table]
. The field names of the GraphQL type of the annotated field must match the column
names of the underlying database table. Thus, if the table has a NAME
column, it
will populate the NAME
field of the GraphQL type.
If the annotated field has arguments, they are used to construct the WHERE
clause of the SQL query. For example, let's look at the following annotated field:
customerById (id: ID!): Customer
@dbquery (
type: "oracle"
schema: "retail"
table: "customers"
configuration: "oracle_config"
)
This example passes the following database query to the database specified by the
oracle_config
configuration (See Managing backend connections for more
information about configurations).
SELECT "id", "name", "email", "creditCard" FROM "retail"."customers" WHERE "id" = ?
where id
, name
, email
and
creditCard
are the columns of the Oracle customers
table that
match the fields of the Customer
type.
If the annotated field has multiple arguments, they are combined in the SQL
WHERE
clause with an AND
.
query
Optional. The value of this argument is the SQL query whose results are used to populate the
sub-fields of the annotated field. While this value is optional, one of either
table
or query
must be specified.
The query
argument is useful when you need to perform a complex query, or when
the table column names and GraphQL type fields do not match. For example:
customerById (id: ID!): Customer
@dbquery (
type: "oracle",
query: 'SELECT "id", "full_name" AS "name", "email" FROM "retail"."customers" WHERE "id" = ? AND "creditCard" IS NOT NULL',
configuration: "oracle_config"
)
The directive executes the specified SQL query
on the database specified by the
oracle_config
. The SQL query both renames full_name
to
name
so it matches the field name in the GraphQL type Customer
,
and retrieves only those customers who have a credit card.
configuration
Required. This argument identifies which configuration in the config.yaml
file
should be used to connect to the database.
An Oracle database configuration contains the url
for connecting to your
database, and will look similar to this:
configurationset:
- configuration:
name: oracle_config
url: jdbc:oracle:thin:[<user>/<password>]@//<host>[:<port>]/<service>
In this example, oracle_config
is the named configuration that will be
referenced by the configuration
property of @dbquery
as
configuration: oracle_config
.
To learn more about the configuration settings for connecting to your Oracle database, see Oracle configuration.