Question

我写了一个查询来获取＆＃39; reason_code＆＃39;和＆＃39; app_count＆＃39;结果集中的前五行和名称＆＃39;其他人的剩余app_count的总和＆＃39;。

我在这里尝试过：

(SELECT a.app_pgm_rsnd_rsn_cd, a.denied_app_count
FROM (SELECT app_pgm_rsnd_rsn_cd ,COUNT(1) as denied_app_count
FROM app_pgm_choice, ead_case 
where app_pgm_sts= 'DN'
AND app_pgm_req_dt >= '20150101'
AND app_pgm_req_dt <= '20150130'
AND EAD_CS_APP_NUM =  APP_PGM_NUM
AND EAD_CS_SEND_CNTY_ID = '19'
AND EAD_CS_TRAN_STS = 'PE'
GROUP BY app_pgm_rsnd_rsn_cd
ORDER BY denied_app_count desc) a
WHERE ROWNUM <=5 )

UNION ALL

(SELECT 'OTHERS' as app_pgm_rsnd_rsn_cd, SUM(b.denied_app_count) as    denied_app_count
FROM (SELECT app_pgm_rsnd_rsn_cd ,COUNT(1) as denied_app_count
FROM app_pgm_choice, ead_case 
where app_pgm_sts= 'DN'
AND app_pgm_req_dt >= '20150101'
AND app_pgm_req_dt <= '20150130'
AND EAD_CS_APP_NUM =  APP_PGM_NUM
AND EAD_CS_SEND_CNTY_ID = '19'
AND EAD_CS_TRAN_STS = 'PE'
GROUP BY app_pgm_rsnd_rsn_cd
ORDER BY denied_app_count desc) b
WHERE ROWNUM >=5 )

但是当我运行此查询时，它会显示以下错误消息：

错误：专栏＆＃34; rownum＆＃34;不存在      第13行：在哪里ROWNUM＆lt; = 5）                ^

**********错误**********

错误：专栏＆＃34; rownum＆＃34;不存在     SQL状态：42703     性格：397

ROWNUM变量的选项是什么？

Answer 1

我认为您正在寻找LIMIT条款。

SELECT * 
FROM sometable 
ORDER BY denied_app_count DESC
LIMIT 5

ROWNUM是Oracle主义。

对于大于号，您可以使用OFFSET：

SELECT * 
FROM sometable 
ORDER BY denied_app_count DESC
OFFSET 5

跳过前5行并返回其余部分。

在做分页等事情时，这两者可以合并，而且往往是合并的。

请参阅LIMIT and OFFSET

在PostgreSQL中你可以使用row_number()窗口函数，但是为了你的目的，这是不必要的。另一方面，使用row_number执行单个查询可能更快，然后查询结果表两次以获得这两个部分。尝试这种方法，看看它是否表现更好。

Answer 2

尝试此查询

(SELECT a.app_pgm_rsnd_rsn_cd, a.denied_app_count
FROM (SELECT app_pgm_rsnd_rsn_cd ,COUNT(1) as denied_app_count
,row_number() OVER (ORDER BY app_pgm_rsnd_rsn_cd ) AS ROWNUM 
FROM app_pgm_choice, ead_case 
where app_pgm_sts= 'DN'
AND app_pgm_req_dt >= '20150101'
AND app_pgm_req_dt <= '20150130'
AND EAD_CS_APP_NUM =  APP_PGM_NUM
AND EAD_CS_SEND_CNTY_ID = '19'
AND EAD_CS_TRAN_STS = 'PE'
GROUP BY app_pgm_rsnd_rsn_cd
ORDER BY denied_app_count desc) a
WHERE ROWNUM <=5 )

UNION ALL

(SELECT 'OTHERS' as app_pgm_rsnd_rsn_cd, SUM(b.denied_app_count) as    denied_app_count
FROM (SELECT app_pgm_rsnd_rsn_cd ,COUNT(1) as denied_app_count
,row_number() OVER (ORDER BY app_pgm_rsnd_rsn_cd ) AS ROWNUM 
FROM app_pgm_choice, ead_case 
where app_pgm_sts= 'DN'
AND app_pgm_req_dt >= '20150101'
AND app_pgm_req_dt <= '20150130'
AND EAD_CS_APP_NUM =  APP_PGM_NUM
AND EAD_CS_SEND_CNTY_ID = '19'
AND EAD_CS_TRAN_STS = 'PE'
GROUP BY app_pgm_rsnd_rsn_cd
ORDER BY denied_app_count desc) b
WHERE ROWNUM >=5 )

如何在PostgreSQL查询中选择特定的行？

2 个答案: