Question

我正在尝试在雪花中运行查询：


SELECT DISTINCT RPU.RID,
RA.DATE,
COALESCE(RTH.CT, 0) as RCNT,
COALESCE (R.COMMENT_SITE, PR.COMMENT_SITE) as COMMENT_SITE,

##########################
COALESCE ((SELECT SPD FROM "DB"."SCHEMA"."PRD" WHERE
           COMMENT_SITE = R.COMMENT_SITE AND CLOTH_ID = RPU.GPR
           ORDER BY (IS_ACTIVE = false) LIMIT 1), PR.SPD) as SPD
#########################
FROM "DB"."SCHEMA"."CLOTH_USED" RPU JOIN "DB"."SCHEMA"."CAGR" RA ON RPU.RID = RA.RID 
LEFT OUTER JOIN "DB"."SCHEMA"."PNTR_IMP" PR ON RPU.COMMENT_ID[1] = PR.ID
left outer join "DB"."SCHEMA"."COMMENTS" R ON RPU.COMMENT_ID[1] = R.ID
LEFT OUTER JOIN CLOTH_COUNT RTH ON RTH.CLOTH_ID = RPU.GPR 
ORDER BY RPU.RID DESC, COALESCE(RTH.CT, 0) ASC, RA.DATE DESC LIMIT 1;

我得到的错误是：

SQL 编译错误：无法评估不受支持的子查询类型

以下查询工作正常：

SELECT DISTINCT RPU.RID,
RA.DATE,
COALESCE(RTH.CT, 0) as RCNT,
COALESCE (R.COMMENT_SITE, PR.COMMENT_SITE) as COMMENT_SITE,
FROM "DB"."SCHEMA"."CLOTH_USED" RPU JOIN "DB"."SCHEMA"."CAGR" RA ON RPU.RID = RA.RID 
LEFT OUTER JOIN "DB"."SCHEMA"."PNTR_IMP" PR ON RPU.COMMENT_ID[1] = PR.ID
left outer join "DB"."SCHEMA"."COMMENTS" R ON RPU.COMMENT_ID[1] = R.ID
LEFT OUTER JOIN CLOTH_COUNT RTH ON RTH.CLOTH_ID = RPU.GPR 
ORDER BY RPU.RID DESC, COALESCE(RTH.CT, 0) ASC, RA.DATE DESC LIMIT 1;

问题SQL 编译错误：无法评估不受支持的子查询类型 在我添加时发生：

COALESCE ((SELECT SPD FROM "DB"."SCHEMA"."PRD" WHERE
           COMMENT_SITE = R.COMMENT_SITE AND CLOTH_ID = RPU.GPR
           ORDER BY (IS_ACTIVE = false) LIMIT 1), PR.SPD) as SPD

如何更正查询？问题在于 where 子句，没有 where 就可以正常工作。如何重写查询？

Answer 1

因此相关的子查询通常可以变成某种形式的连接，如果您正在做的主要事情是在两列上进行匹配并选择随机出现的内容（如果您有超过 1 行处于 active=false 状态）行，这可以变成一个 row_number() 并使用 QUALITY 作为等价物作为 LIMIT。

因此：

WITH sub_query AS (
    SELECT 
        spd
        comment_site
        cloth_id
    FROM db.schema.prd
    QUALIFY row_number() OVER (PARTITION BY comment_site, cloth_id ORDER BY IS_ACTIVE = false) = 1
)
SELECT DISTINCT 
    rpu.rid,
    ra.date,
    COALESCE(rth.ct, 0) AS rcnt,
    COALESCE (r.comment_site, pr.comment_site) AS comment_site,

    COALESCE ( sq.spd, pr.spd) as SPD

FROM DB.schema.cloth_used AS rpu 
JOIN db.schema.cagr  AS ra 
    ON rpu.rid = ra.rid 
LEFT OUTER JOIN db.schema.pntr_imp AS pr 
    ON rpu.comment_id[1] = pr.id
LEFT OUTER JOIN db.schema.comments AS r 
    ON rpu.comment_id[1] = r.id
LEFT OUTER JOIN sub_query AS sq
    ON sq.comment_site = r.comment_site AND sq.cloth_id = rpu.gpr
LEFT OUTER JOIN cloth_count AS rth 
    ON RTH.CLOTH_ID = RPU.GPR 
ORDER BY rpu.rid DESC, COALESCE(rth.ct, 0) ASC, ra.date DESC 
LIMIT 1;

应该可以满足您的需求，现在我使用了 CTE，但如果您愿意或需要，可以将其移至 JOIN 区域：

SELECT DISTINCT 
    rpu.rid,
    ra.date,
    COALESCE(rth.ct, 0) AS rcnt,
    COALESCE (r.comment_site, pr.comment_site) AS comment_site,

    COALESCE ( sq.spd, pr.spd) as SPD

FROM DB.schema.cloth_used AS rpu 
JOIN db.schema.cagr  AS ra 
    ON rpu.rid = ra.rid 
LEFT OUTER JOIN db.schema.pntr_imp AS pr 
    ON rpu.comment_id[1] = pr.id
LEFT OUTER JOIN db.schema.comments AS r 
    ON rpu.comment_id[1] = r.id
LEFT OUTER JOIN (
    SELECT 
        spd
        comment_site
        cloth_id
    FROM db.schema.prd
    QUALIFY row_number() OVER (PARTITION BY comment_site, cloth_id ORDER BY IS_ACTIVE = false) = 1
) AS sq
    ON sq.comment_site = r.comment_site AND sq.cloth_id = rpu.gpr
LEFT OUTER JOIN cloth_count AS rth 
    ON RTH.CLOTH_ID = RPU.GPR 
ORDER BY rpu.rid DESC, COALESCE(rth.ct, 0) ASC, ra.date DESC 
LIMIT 1;

雪花中不支持的子查询

1 个答案: