DB2使用带标签的持续时间对多个日期间隔无效

Question

I'm trying to refactor a MySQL query to run on DB2/iSeries and I'm getting the error Use of labeled duration not valid.

Looking at the documentation I feel like the usage below should be working.

Am I missing something?

SELECT
    IFNULL(SUM(CASE WHEN CURDATE() BETWEEN n.start_date AND n.expire_date
                    THEN 1 ELSE 0 END), 0) AS current,
    IFNULL(SUM(CASE WHEN CURDATE() -  365 DAY BETWEEN n.start_date AND n.expire_date
                    THEN 1 ELSE 0 END), 0) AS prior,
    IFNULL(SUM(CASE WHEN '2018-12-31' -  7 DAY BETWEEN n.start_date AND n.expire_date
                    THEN 1 ELSE 0 END), 0) AS full
FROM salesnumbers;

Answer 1

The issue is likely your date intervals. Try using CURRENT DATE instead of CURDATE() . Also, you may list date intervals +/- some amount directly in DB2.

SELECT
    COUNT(CASE WHEN CURRENT DATE BETWEEN n.start_date AND n.expire_date
               THEN 1 END) AS current,
    COUNT(CASE WHEN CURRENT DATE -  1 YEAR BETWEEN n.start_date AND n.expire_date
               THEN 1 END) AS prior,
    COUNT(CASE WHEN DATE('2018-12-31') - 7 DAY BETWEEN n.start_date AND n.expire_date
               THEN 1 END) AS full
FROM salesnumbers;

Note that I replaced your conditional sums with conditional counts. This leaves the code slightly more terse, because we don't have to spell out an explicit ELSE condition (the default being NULL ).