CASE WHEN KSDM = SJKS THEN TO_CHAR(KSDM) ELSE SJKS ||'/'|| KSDM END AS path,

这是一条 SQL 语句，也是用于根据条件判断生成一个新的字段。

- 当 KSDM 等于 SJKS 时，path 字段的值为 KSDM 的字符串表示。
- 当 KSDM 不等于 SJKS 时，path 字段的值为 SJKS 字段的字符串表示和 KSDM 字段的字符串表示通过斜杠（/）拼接而成。其中 TO_CHAR 函数用于将 KSDM 字段转换为字符串类型。

相关问题

优化select e.ygxm as zkysxm, count(*) as total from (select a.ksdm, a.zkys, (select a.ksdm from ms_ghmx where sbxh = a.zkgl) as zkqks from ms_ghmx a where a.ghly = 4 and a.ghsj >= TO_TIMESTAMP('2016-08-01 00:00:00', 'YYYY-MM-DD HH24:MI:SS') AND a.ghsj < TO_TIMESTAMP('2023-05-23 23:59:59', 'YYYY-MM-DD HH24:MI:SS')) b left join gy_ksdm c on b.ksdm = c.ksdm left join gy_ksdm d on b.zkqks = d.ksdm left join gy_ygdm e on b.zkys = e.ygdm group by e.ygxm order by zkysxm

可以考虑以下优化：

1. 尽量避免子查询，可以将子查询的结果存储到临时表中，再进行查询。

2. 使用JOIN代替子查询，因为JOIN通常比子查询更快。

3. 如果可能的话，使用索引来加速JOIN操作。

4. 将WHERE条件中的时间格式转换提前处理，以避免在查询时进行转换。

5. 避免使用通配符（如SELECT *），只选择需要的列。

基于以上优化建议，可以将原查询进行改写：

CREATE TEMPORARY TABLE temp_table AS (
    SELECT 
        a.ksdm, 
        a.zkys, 
        m.zkqks 
    FROM 
        ms_ghmx a 
        LEFT JOIN (
            SELECT 
                sbxh, 
                ksdm AS zkqks 
            FROM 
                ms_ghmx
        ) m ON a.zkgl = m.sbxh 
    WHERE 
        a.ghly = 4 
        AND a.ghsj >= '2016-08-01 00:00:00' 
        AND a.ghsj < '2023-05-23 23:59:59'
);

SELECT 
    e.ygxm AS zkysxm, 
    COUNT(*) AS total 
FROM 
    temp_table t 
    LEFT JOIN gy_ksdm c ON t.ksdm = c.ksdm 
    LEFT JOIN gy_ksdm d ON t.zkqks = d.ksdm 
    LEFT JOIN gy_ygdm e ON t.zkys = e.ygdm 
GROUP BY 
    e.ygxm 
ORDER BY 
    zkysxm;

这个改写可能不是最优解，但可以作为一种参考方案。需要根据实际情况进行调整和优化。

SELECT * FROM ( SELECT GY_YLSF.FYMC AS FYMC, GY_YLSF.FYDW AS FYDW, MS_YJ02.YLSL AS FYSL, MS_YJ02.YLDJ AS FYDJ, MS_YJ02.ZFBL AS ZFBL, (MS_YJ02.ZFBL * MS_YJ02.YLDJ * MS_YJ02.YLSL) as zje, ( MS_YJ02.YLDJ * MS_YJ02.YLSL) as zje1, GY_YGDM.YGXM AS YGXM, MS_YJ01.brxm as brxm, ms_mzxx.jzrq as jzrq, MS_YJ02.fygb as fygb, YYGH_GHJL.fzbz as fzbz, GY_YLSF.srfl as srfl, ms_brda.mzhm, MS_YJ01.ysdm, GY_YGDM.ygbh, ms_mzxx.sfrq, gy_ksdm.KSMC, MS_YJ01.BRXZ, MS_BRDA.BRID, (select dmmc from GY_YLSF a,GY_DMZD b where a.FYXH = GY_YLSF.FYXH and a.srfl = b.DMSB and b.DMLB = 1177 )sffl FROM MS_YJ02, GY_YLSF, MS_YJ01, GY_YGDM, gy_ksdm, ms_mzxx, ms_brda, YYGH_GHJL WHERE ( GY_YLSF.FYXH = MS_YJ02.YLXH ) AND ( MS_YJ01.YJXH = MS_YJ02.YJXH ) AND ( MS_YJ01.YSDM = GY_YGDM.YGDM ) AND (gy_ksdm.ksdm = MS_YJ01.ksdm )and ( ms_yj01.brid = ms_brda.brid )and ( ms_mzxx.ZFPB = 0 ) AND (ms_yj01.fphm = ms_mzxx.fphm) and (YYGH_GHJL.GHLSH = MS_YJ01.GHLSH) and ( MS_YJ01.FJLB IS NULL OR MS_YJ01.FJLB = 0 ) and (MS_YJ01.FPHM is not null )

这是一个 SQL 查询语句，可能是用于查询医院的费用信息。它使用了多个表之间的关联条件，包括挂号记录、医技申请单、医生信息、科室信息、门诊信息等等。查询结果包括费用名称、单位、数量、单价、自负比例、总金额、医生姓名、病人姓名、结算日期、费用归并、费别、收入分类、门诊号码、医生代码、医工编号、收费日期、科室名称、病人性质、病人ID等信息。