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System variables referenceBigQuery supports the following system variables for multi-statement queries or within sessions. You can use system variables to set or retrieve information during query execution, similar to user-defined procedural language variables.
Name Type Read and write or read-only Description@@current_job_id STRING Read-only Job ID of the currently executing job. In the context of a multi-statement query, this returns the job responsible for the current statement, not the entire multi-statement query. @@dataset_id STRING Read and write ID of the default dataset in the current project. This ID is used when a dataset is not specified for a project in the query. You can use the SET statement to assign @@dataset_id to another dataset ID in the current project. The system variables @@dataset_project_id and @@dataset_id can be set and used together. @@dataset_project_id STRING Read and write ID of the default project that's used when one is not specified for a dataset used in the query. If @@dataset_project_id is not set, or if it is set to NULL, the query-executing project (@@project_id) is used. You can use the SET statement to assign @@dataset_project_id to another project ID. The system variables @@dataset_project_id and @@dataset_id can be set and used together. @@last_job_id STRING Read-only Job ID of the most recent job to execute in the current multi-statement query, not including the current one. If the multi-statement query contains CALL statements, this job may have originated in a different procedure. @@location STRING Read and write The location in which to run the query. @@location can only be set to a string literal with a valid location. A SET @@location statement must be the first statement in a query. An error occurs if there is a mismatch between @@location and another location setting for the query. You can improve the latency of queries that set @@location by using optional job creation mode. You can use the @@location system variable inside of SQL UDFs and table functions. @@project_id STRING Read-only ID of the project used to execute the current query. In the context of a procedure, @@project_id refers to the project that is running the multi-statement query, not the project which owns the procedure. @@query_label STRING Read and write Query label to associate with query jobs in the current multi-statement query or session. If set in a query, all subsequent query jobs in the script or session will have this label. If not set in a query, the value for this system variable is NULL. For an example of how to set this system variable, see Associate jobs in a session with a label. @@reservation STRING Read and write [Preview]. Specifies the reservation where the job is run. Must be in the following format: projects/project_id/locations/location/reservations/reservation_id. The location of the reservation must match the location the query is running in. @@row_count INT64 Read-only If used in a multi-statement query and the previous statement is DML, specifies the number of rows modified, inserted, or deleted, as a result of that DML statement. If the previous statement is a MERGE statement, @@row_count represents the combined total number of rows inserted, removed, and deleted. This value is NULL if not in a multi-statement query. @@script.bytes_billed INT64 Read-only Total bytes billed so far in the currently executing multi-statement query job. This value is NULL if not in the job. @@script.bytes_processed INT64 Read-only Total bytes processed so far in the currently executing multi-statement query job. This value is NULL if not in the job. @@script.creation_time TIMESTAMP Read-only Creation time of the currently executing multi-statement query job. This value is NULL if not in the job. @@script.job_id STRING Read-only Job ID of the currently executing multi-statement query job. This value is NULL if not in the job. @@script.num_child_jobs INT64 Read-only Number of currently completed child jobs. This value is NULL if not in the job. @@script.slot_ms INT64 Read-only Number of slot milliseconds used so far by the script. This value is NULL if not in the job. @@session_id INT64 Read-only ID of the session that the current query is associated with. @@time_zone STRING Read and write The default time zone to use in time zone-dependent SQL functions, when a time zone is not specified as an argument. @@time_zone can be modified by using a SET statement to any valid time zone name. At the start of each script, @@time_zone begins as “UTC”.
For backward compatibility, expressions used in an OPTIONS or FOR SYSTEM TIME AS OF clause default to the America/Los_Angeles time zone, while all other date/time expressions default to the UTC time zone. If @@time_zone has been set earlier in the multi-statement query, the chosen time zone will apply to all date/time expressions, including OPTIONS and FOR SYSTEM TIME AS OF clauses.
In addition to the system variables shown previously, you can use EXCEPTION system variables during execution of a multi-statement query. For more information about the EXCEPTION system variables, see the procedural language statement BEGIN...EXCEPTION.
You don't create system variables, but you can override the default value for some of them:
SET @@dataset_project_id = 'MyProject';
The following query returns the default time zone:
SELECT @@time_zone AS default_time_zone;
+-------------------+
| default_time_zone |
+-------------------+
| UTC |
+-------------------+
You can use system variables with DDL and DML queries. For example, here are a few ways to use the system variable @@time_zone when creating and updating a table:
BEGIN
CREATE TEMP TABLE MyTempTable
AS SELECT @@time_zone AS default_time_zone;
END;
CREATE OR REPLACE TABLE MyDataset.MyTable(default_time_zone STRING)
OPTIONS (description = @@time_zone);
UPDATE MyDataset.MyTable
SET default_time_zone = @@time_zone
WHERE TRUE;
There are some places where system variables can't be used in DDL and DML queries. For example, you can't use a system variable as a project name, dataset, or table name. The following query produces an error when you include the @@dataset_id system variable in a table path:
BEGIN
CREATE TEMP TABLE @@dataset_id.MyTempTable (id STRING);
END;
For more examples of how you can use system variables in multi-statement queries, see Set a variable.
For examples of how you can use system variables in sessions, see Example session.
Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. For details, see the Google Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.
Last updated 2025-08-07 UTC.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-07 UTC."],[[["BigQuery system variables allow setting or retrieving information during query execution in multi-statement queries or sessions, similar to user-defined procedural language variables."],["System variables have different types such as `STRING`, `INT64`, and `TIMESTAMP`, and can be either read-only or allow read and write access."],["Some system variables are specific to multi-statement queries (e.g., `@@row_count`, `@@script.bytes_billed`), while others relate to the current project, dataset, or session (e.g., `@@project_id`, `@@dataset_id`, `@@session_id`)."],["Certain system variables like `@@dataset_project_id`, `@@dataset_id`, `@@location`, `@@query_label`, and `@@time_zone` can be modified using the `SET` statement to override default values."],["While system variables are useful in DDL and DML queries, they cannot be used as project, dataset, or table names in such queries."]]],[]]
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