# System variables in BigQuery

Today's quick post is about system variables in BigQuery. What are they?

They are a special type of variables, available in scripts (multi-statement queries). You can use them to read (and sometimes write) query metadata during query execution.

Here's a couple of examples:  
\- `@@query_label` - read/write query labels, making easier for you to group your queries based on they are used for  
\- `@@time_zone` - read/write default time zone to use  
\- `@@script.job_id` - the job id of the current job

Check out below an example with slot\_ms (returns slot time in millis), bytes\_billed and creation\_date.

![](https://miro.medium.com/v2/resize:fit:700/0*IQjiIlhLlwCgBMJW align="left")

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