如何在mysql中使用查询获取一条记录的多条记录

Question

How to be able to query from this data:

parking_place | number_of_month  | from_date | end_date  | monthly_unit_price
A             | 3                | 2018-01   | 2018-03   | 3000000

Desire to show results:

parking_place | month   | monthly_unit_price
A             | 2018-01 | 3000000
A             | 2018-02 | 3000000
A             | 2018-03 | 3000000

please suggest me how to query?

Answer 1

You may join using a calendar table:

SELECT
    t.parking_place,
    t.month,
    t.monthly_unit_price
FROM
(
    SELECT '2018-01' AS month UNION ALL
    SELECT '2018-02' UNION ALL
    SELECT '2018-03'
) months
INNER JOIN yourTable t
    ON months.month BETWEEN t.from_date AND t.end_date
ORDER BY
    months.month;

Note that it would be better to store actual valid date literals to represent each month. For example, instead of storing the text '2018-01' , you could store 2018-01-01 as a date literal.