Querying multiple tables in Big Query

One SQL query can reference multiple tables. Just separate each table with a comma in the FROM clause to query across all mentioned tables.

You can also use a Table Wildcard Function. Here's one example from the docs for StandardSQL:

SELECT 
  name
FROM 
  mydata.people
WHERE 
  age >= 35
  AND
  (_TABLE_SUFFIX BETWEEN '20140325' AND '20140327')

And here's a similar example for LegacySQL (docs).

SELECT 
  name
FROM 
  (TABLE_DATE_RANGE([mydata.people], 
                TIMESTAMP('2014-03-25'), 
                TIMESTAMP('2014-03-27'))) 
WHERE 
  age >= 35

This will query the tables:

• mydata.people20140325
• mydata.people20140326
• mydata.people20140327

There are a few other options on the docs. I'd recommend checking them out.