多 sql select 语句

Question

我有一个 table 这种：

| name    |  salary |  day  |  month   |
| james   |  200.00 |    2  | january  |
| marie   |  400.00 |    4  | january  |
| jimmy   |  300.00 |    7  | january  |
| Fredd   |  700.00 |    3  | february |
| rosieli |  500.00 |    5  | february |
| rosela  |  800.00 |    6  | february |

如果 table 名称是 'db_table'，我如何将 sql select 查询写入 select 从 1 月 4 日到 2 月 5 日的记录。
类似于：

select * from db_table between day='4',month='january' and day='5' and month='february'";

请问我如何编写正确的 sql 语句来获得所需的 results.so table 如下所示：

| name    |  salary |  day  |  month   | 
| marie   |  400.00 |    4  | january  |
| jimmy   |  300.00 |    7  | january  |
| Fredd   |  700.00 |    3  | february |
| rosieli |  500.00 |    5  | february |

谢谢

Answer 1

您必须从 month 和 day 中创建一个可比较的字符串以在 between 语句中使用：

select * from db_table where 
concat(case month 
         when 'january' then '01'
         when 'february' then '02'
         ........................
         when 'december' then '12'
       end, case when day < 10 then '0' else '' end, day) between '0104' and '0205'

像这样，您可以通过仅修改开始日期和结束日期来比较任何日期范围。

Answer 2

how do I write an sql select query to select records from 4th January to 5th February.

select  *
from    db_table
where   (month = 'january' and 4 <= cast(day as int)) or
        (month = 'february' and cast(day as int) <= 5)

请注意，table 具有单独的月份和日期列的设计使得查询变得困难。在年份界限上会变得更加困难。更好的设计是使用数据库的本机日期时间列类型。然后你可以这样查询：

select  *
from    db_table
where   dt_col between '2019-01-04' and '2019-02-05'

Answer 3

您需要将日期设为数字，但就是这样：

SELECT *
FROM db_table
WHERE (day >= 4 and month = 'January')
   OR (day <= 5 and month = 'February')

例如一月到四月：

SELECT *
FROM db_table
WHERE (day >= 4 and month = 'January')
   OR (day <= 5 and month = 'April')
   OR month IN ('February','March')

Answer 4

你真的应该使用日期来做到这一点。

select t.*
from t
where str_to_date(concat_ws(2020, month, day), '%Y %M %d') between '2020-01-04' and '2020-02-05';

如果可能，应使用日期进行日期比较。

我用的是2020因为是闰年所以会处理2月29日

解决此问题后，您应该修复数据模型以包含实际日期而不是 month/day 组合。

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