flink sql求本周一到周日日期函数

Flink SQL中可以使用`DATE_FORMAT`和`DATE_SUB`函数来计算本周一到周日的日期。具体实现如下：

SELECT
  DATE_FORMAT(DATE_SUB(CURRENT_DATE(), DAYOFWEEK(CURRENT_DATE()) - 2), 'yyyy-MM-dd') AS monday,
  DATE_FORMAT(DATE_SUB(CURRENT_DATE(), DAYOFWEEK(CURRENT_DATE()) - 3), 'yyyy-MM-dd') AS tuesday,
  DATE_FORMAT(DATE_SUB(CURRENT_DATE(), DAYOFWEEK(CURRENT_DATE()) - 4), 'yyyy-MM-dd') AS wednesday,
  DATE_FORMAT(DATE_SUB(CURRENT_DATE(), DAYOFWEEK(CURRENT_DATE()) - 5), 'yyyy-MM-dd') AS thursday,
  DATE_FORMAT(DATE_SUB(CURRENT_DATE(), DAYOFWEEK(CURRENT_DATE()) - 6), 'yyyy-MM-dd') AS friday,
  DATE_FORMAT(DATE_SUB(CURRENT_DATE(), DAYOFWEEK(CURRENT_DATE()) - 7), 'yyyy-MM-dd') AS saturday,
  DATE_FORMAT(CURRENT_DATE(), 'yyyy-MM-dd') AS sunday
FROM
  (
    SELECT 1 AS id
  ) t

其中，`DAYOFWEEK`函数可以获取当前日期是星期几，从而计算出本周一到周日的日期。`DATE_SUB`函数可以在当前日期的基础上减去相应的天数，从而得到所求日期。`DATE_FORMAT`函数可以将日期转换为指定格式的字符串。