Question

我需要将VALUE_Expiration_DATE附加到DATE_EXPERATON 我的表有4个字段：

--- REFERENCE --- DATE (Production or EXPIRATION) --- COUNTRY --- VALUE --- 

---- 1  ----------------------- 1014 (production) -------------------- CAN   ---------- 105 -------   
---- 1  ----------------------- 0215 (expiration) --------------------- CAN    ---------- 203 -
.............................................    ............................................................................

我的问题是如何在同一行获取2日期PROD和EXP的值，这对我来说不起作用：

SELECT 
  REFERENCE
  ,@PARAM_Production_DATE AS Production_DATE
  ,@PARAM_Expiration_DATE AS Expiration_DATE    
  ,COUNTRY  
  ,VALUE AS VALUE_Production_DATE   
  ,**(
   SELECT 
      value 
    FROM PRODUCT 
WHERE REFERENCE <> 'XXX'
AND DATE in (@PARAM_Expiration_DATE)
) AS VALUE_Expiration_DATE** 
FROM PRODUCT
WHERE REFERENCE <> 'XXX'
AND DATE in (@PARAM_Production_DATE)

以粗体显示的行不起作用，因为它返回的值超过1。我该怎么办呢。

Answer 1

您只是忘记了子查询中对主查询的引用（即确保访问相同的REFERENCE）：

SELECT 
  REFERENCE
  ,@PARAM_Production_DATE AS Production_DATE
  ,@PARAM_Expiration_DATE AS Expiration_DATE    
  ,COUNTRY  
  ,VALUE AS VALUE_Production_DATE   
  ,(
   SELECT 
      value 
    FROM PRODUCT p2
    WHERE p2.REFERENCE = p1.REFERENCE
    AND DATE in (@PARAM_Expiration_DATE)
   ) AS VALUE_Expiration_DATE 
FROM PRODUCT p1
WHERE REFERENCE <> 'XXX'
AND DATE in (@PARAM_Production_DATE);

您可以使用左连接执行相同的操作：

select 
   production.reference
  ,production.date as production_date
  ,@param_expiration_date as expiration_date    
  ,production.country  
  ,production.value as value_production_date   
  ,expiration.value as value_expiration_date
from product production
left join product expiration
  on expiration.reference = production.reference and expiration.date = @param_expiration_date
where production.date = @param_production_date
and production.reference <> 'XXX';

加入相同的表SQL

1 个答案: