DataEase2.10.18版本判断动态传参的参数是否为空

DataEase
1 
SELECT YEAR(t.end_date) AS yr, COUNT(DISTINCT t.kkh) AS total_cnt
FROM t_kkqk t
WHERE YEAR(t.end_date) BETWEEN 2021 AND 2025
  AND t.skjsgh IS NOT NULL
  AND TRIM(t.skjsgh) <> ''

AND (
(‘$[zydm]’ = ‘’ AND ‘$[xndwh]’ = ‘’) – 两个都不传：不 EXISTS，全校 kkh
OR (
(‘$[zydm]’ <> ‘’ OR ‘$[xndwh]’ <> ‘’) – 至少传一个：才 EXISTS
AND EXISTS (
SELECT 1
FROM filtered_jzg p
WHERE p.yr = YEAR(t.end_date)
AND CONCAT(‘;’, TRIM(t.skjsgh), ‘;’) LIKE CONCAT(‘%;’, p.gh, ‘;%’)
)
)
)
GROUP BY YEAR(t.end_date)，这段sql中的zydm、xndwh这两个动态参数如何判断是否为空，目前这种写法不行