MySQL:基于日期范围的计算列

Question

如何创建一个计算列，如果日期在 2015 年以内则返回值 1，否则返回 0？

我昨天用谷歌搜索和搜索 StackOverflow 寻找解决方案，但无济于事。根据我对 CASE WHEN、BETWEEN 和 CAST 的了解，我将以下 SQL 脚本放在一起。

然而，尽管在 2015 年、2016 年有相应的 Prescreen 日期，甚至日期为 0000-00-00，但下面的(截断的)脚本会产生全 0，如下所示:

SELECT 
table_r.R_Number,
table_c.ref_num,
DATE(STR_TO_DATE(table_c.Prescreen, '%d-%b-%y')) AS Prescreen,
CASE
    WHEN Prescreen BETWEEN CAST('2015-01-01' AS DATE) AND CAST('2015-12-31' AS DATE) THEN 1
    ELSE 0
END AS YTD2015_Prescreen,
table_r.Region,
FROM
table_c
    INNER JOIN
table_r ON table_c.R_Number = table_r.R_Number
WHERE
table_c.Int <> ''
;

我谦虚地请求你把你的天才借给我。谢谢。 :)

Answer 1

试试这个:

    SELECT 
    table_r.R_Number,
    table_c.ref_num,
    STR_TO_DATE(table_c.Prescreen,'%d-%b-%y') AS Prescreen,
    CASE
    WHEN STR_TO_DATE(table_c.Prescreen,'%d-%b-%y')  BETWEEN CAST('20150101'AS DATE) AND CAST('20151231' AS DATE) THEN 1
    ELSE 0
    END AS YTD2015_Prescreen,
    table_r.Region,
    FROM
    table_c
        INNER JOIN
    table_r ON table_c.R_Number = table_r.R_Number
    WHERE
    table_c.Int <> ''
    ;