I’ve noticed that CURRENT is a reserved keyword for BigQuery at: https://cloud.google.com/bigquery/docs/reference/standard-sql/lexical.
What exactly does CURRENT do? I’ve only seen it as a prefix for things such as CURRENT_TIME(), CURRENT_DATE(), and other such stuff but have never seen it by itself. Is this just reserved for future usage or do any SQL statements contain that as a keyword?
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Answer
Just to add on the comment of @Jaytiger:
CURRENT keyword seems to be reserved as a part of SQL 2016 spec. en.wikipedia.org/wiki/SQL_reserved_words And you can check it’s usage in another DBMS implementations like Oracle, SQL Server. hope this is helpful. stackoverflow.com/questions/49110728/where-current-of-in-pl-sql
In BigQuery CURRENT clause is used on defining frame_start and frame_end in window functions.
A window function, also known as an analytic function, computes values over a group of rows and returns a single result for each row.
A common usage for this is calculating a cumulative sum for each category in the table. See BigQuery window function examples for reference.