Duplicate each row pulled in and add an extra field counting up one day between a given start and end date

问题

I'm using Microsoft Access and I want to create a query that duplicates each row pulled in from a table with an extra field added on counting up one day between a given start and end date.

So if there's 4 days between the start and end date there's 4 duplicate rows returned for each record with only difference being the added date field counting up 1 day.

Is this actually possible to do?

回答1:

This task is fairly easy if you have a calendar table which includes a row for each date you need. (See this Stack Overflow answer for other reasons why a calendar table can be useful.) Without such a table, this task is not practical with Access SQL.

Using my calendar table and this sample data in YourTable ...

fld1 start_date end_date
---- ---------- ----------
a    12/26/2013 12/26/2013
b    12/27/2014 12/28/2014
c      1/1/2014   1/3/2014
d      1/4/2014   1/1/2014

... the query below gave me this output.

fld1 start_date end_date   added_date
---- ---------- ---------- ----------
a    12/26/2013 12/26/2013 12/26/2013
b    12/27/2014 12/28/2014 12/27/2014
b    12/27/2014 12/28/2014 12/28/2014
c      1/1/2014   1/3/2014   1/1/2014
c      1/1/2014   1/3/2014   1/2/2014
c      1/1/2014   1/3/2014   1/3/2014

Notice the "d" row was not included in the output because end_date was earlier than start_date in that row. You can include a table-level validation rule to enforce the requirement that start_date <= end_date in every row.

SELECT
    y.fld1,
    y.start_date,
    y.end_date,
    c.the_date AS added_date
FROM
    tblCalendar AS c
    INNER JOIN YourTable AS y
    ON
            c.the_date >= y.start_date
        AND c.the_date <= y.end_date
ORDER BY
    y.fld1,
    c.the_date;

来源：https://stackoverflow.com/questions/20923437/duplicate-each-row-pulled-in-and-add-an-extra-field-counting-up-one-day-between

标签

ms-access

ms-access-2007

ms-access-2010