BigQuery标准SQL：从时间戳中提取星期几名称

Question

我正在使用BigQuery 标准SQL。

我需要将时间戳转换为星期几名称。

例如转换今天的时间戳（2016年11月24日00:00:00）到一个字符串：“周四”

谢谢:)

Answer 1

你必须使用DAYOFWEEK（），然后CASE语句返回星期几。 DAYOFWEEK（）将星期几作为1（星期日）至7（星期六）之间的整数。 Date and time functions

例如

SELECT 
    CASE 
    WHEN DAYOFWEEK(CURRENT_DATE()) = 1 THEN 'Sunday' 
    WHEN DAYOFWEEK(CURRENT_DATE()) = 2 THEN 'Monday' 
    WHEN DAYOFWEEK(CURRENT_DATE()) = 3 THEN 'Tuesday' 
    WHEN DAYOFWEEK(CURRENT_DATE()) = 4 THEN 'Wednesday' 
    WHEN DAYOFWEEK(CURRENT_DATE()) = 5 THEN 'Thursday' 
    WHEN DAYOFWEEK(CURRENT_DATE()) = 6 THEN 'Friday' 
    WHEN DAYOFWEEK(CURRENT_DATE()) = 7 THEN 'Saturday' 
    END Weekday 

Answer 2

下面是BigQuery的标准SQL

#standardSQL 
SELECT 
    CURRENT_DATE() AS day, 
    FORMAT_DATE('%a', CURRENT_DATE()) AS weekday_name_abbreviated, 
    FORMAT_DATE('%A', CURRENT_DATE()) AS weekday_name_full 

或

#standardSQL 
SELECT 
    DATE('2016-11-24 00:00:00') AS day, 
    FORMAT_DATE('%a', DATE('2016-11-24 00:00:00')) AS weekday_name_abbreviated, 
    FORMAT_DATE('%A', DATE('2016-11-24 00:00:00')) AS weekday_name_full 

结果是

day   weekday_name_abbreviated weekday_name_full  
2016-11-24 Thu       Thursday