How to get Day name in Google BigQuery
In Google's Big Query, the function to use is: format_datetime('%A',yourdate) instead of format_date as posted in 2017.
Yes, there are equivalent functions in both, standardSQL and legacySQL.
Standard SQL
You can use the FORMAT_DATE() function where you can use any date format you'd like. Link to Docs
Example:
#standardSQL
SELECT
CURRENT_DATE() AS date,
FORMAT_DATE('%A', CURRENT_DATE()) AS dow
Legacy SQL
There is the STRFTIME_UTC_USEC() function. It requires converting your timestamp to USEC first though. Link to docs
Example:
#legacySQL
SELECT
CURRENT_DATE() AS date,
STRFTIME_UTC_USEC(TIMESTAMP_TO_USEC(TIMESTAMP(CURRENT_DATE())), '%A') AS dow