MySQL中或者sql sever中如何取得日期字段的天数

Question

MySQL中或者sql sever中如何取得日期字段的天数，先要返回对应月份的天数，然后用累计工时字段/天数字段=日平均工时
请问需要怎么实现？

SELECT
    field0019 AS 工作日期,
    field0020 AS 年月,            -- 此处年月为文本数据类型
    field0005 AS 类型,
    field0006 AS 品牌,
    field0007 AS 型号,
    field0001 AS 整机编号,
    field0008 AS 缩写编号,
    field0009 AS 累计表时,
    field0021 AS 本日运作工时,
    field0022 AS 本日出勤情况,
    field0010 AS 累计出勤,
    field0009/field0010 AS 平均工作时长
FROM
    formmain_18477 AS a
    LEFT JOIN formson_18480 AS b ON b.formmain_id = a.id 
ORDER BY
    b.field0019
    
--取field0020 年月字段返回的当月天数，从而求得field0009累计表时间/当月天数=日平均工时

Answer 1

MySQL

select day(@dt)

sql sever

select DATENAME(DAY,@dt)

其中@dt，是你的字段名