trying to query a data table via losant rest api, but where can I find which id a table has?
You can find the ID of a data table in your URL when visiting the table in the web interface -
https://app.losant.com/applications/APPLICATION_ID/data-tables/DATA_TABLE_ID
If you don’t want to use the web interface, you could first make an API call to retrieve your application’s list of data tables, and you’ll find IDs for each in that result.