Crystal Reports-加入表

Question

我有一个问题，我有4个需要连接的表，我已经为其中3个进行了连接（让它们称为table1，table2，table3），直到此点正常工作为止，连接都伴随着问题。最后一张表，在这里我需要询问表4上是否存在一条记录（这是外键'的组合，用于连接其他3个表的键与一个附加的列值，但并非所有记录都记录下来），然后如果记录存在于表4中，我需要显示其内容“来自table4的一个特定列”，否则仅将其显示为空白。有人做过吗？

这是具有前三个表联接的查询。

SELECT
TABLE1.NUMPROD as BATCH_ID,
TABLE2.EQPCODE as Tank,
TABLE1.CODEPROD as Product_Code,
TABLE1.XFIELD_03 as Sequence,
TABLE3.ITEM_CONSUMED as ITEM,
TABLE3.CONSUMPTION_QUANTITY as QUANTITY

FROM 
TABLE1 
INNER JOIN TABLE3 on TABLE1.NUMPROD = TABLE3.ORDERID
INNER JOIN TABLE2 ON TABLE3.ORDERID = TABLE2.NUMBERLOT

AND TABLE1.ETAT = 'F' 
AND TABLE1.DATECREATION BETWEEN ('20191001') AND ('20191004') 
AND TABLE1.XFIELD_03 IS NOT NULL
AND TABLE3.CONSUMPTION_QUANTITY > 0 
and TABLE2.VALUE = 'ASSIGNED'

Answer 1

类似这样的事情：

SELECT
TABLE1.NUMPROD as BATCH_ID,
...
TABLE3.CONSUMPTION_QUANTITY as QUANTITY,
--                                           --> from this line ...
(select some_column 
 from table4 t4
 where t4.some_id = table1.some_other_Id
) table_4_column                      
--                                           --> ... to this line
FROM 
TABLE1 JOIN ...

从table4获取数据的查询必须返回最多一个值；否则，将出现too-many-rows错误。