Which of the following statements about Legacy SQL and Standard SQL is not true?

Which of the following statements about Legacy SQL and Standard SQL is not true?
A . Standard SQL is the preferred query language for BigQuery.
B . If you write a query in Legacy SQL, it might generate an error if you try to run it with Standard SQL.
C . One difference between the two query languages is how you specify fully-qualified table names (i.e. table names that include their associated project name).
D . You need to set a query language for each dataset and the default is Standard SQL.

Answer: D

Explanation:

You do not set a query language for each dataset. It is set each time you run a query and the default query language is Legacy SQL.

Standard SQL has been the preferred query language since BigQuery 2.0 was released.

In legacy SQL, to query a table with a project-qualified name, you use a colon, :, as a separator. In standard SQL, you use a period, ., instead.

Due to the differences in syntax between the two query languages (such as with project-qualified table names), if you write a query in Legacy SQL, it might generate an error if you try to run it with Standard SQL.

Reference: https://cloud.google.com/bigquery/docs/reference/standard-sql/migrating-from-legacy-sql