如何在选择查询中生成空字段 [英] How do I produce a null field in a select query

问题描述

我在下面的查询中给出了结果

I have this below query which gives the result

Select distinct a.Item_Name, b.Item_Rate, b.professional_Charge, c.discount ,  c.discount_Type,
a.Dept_ID, c.Discount_Applicability
From Item_M a
left outer join Rate_M  b on a.Item_Code = b.Bill_Item
left outer join Discount_M c on a.Item_Code = c.Item_Code
Where a.Item_code = 'ABS002' and b.Rate_Cat_ID = 'DLX' and
c. Pay_Type_Id='BD'

Item_Name    Item_Rate   professional_Charge	discount	discount_Type	Dept_ID	Discount_Applicability
ABSESS I & D    	440	NULL	0	P	CBN	I

当我更改a.Item_code时，
将显示空白结果，除非Item_M中有项目代码table是一个完美的查询执行示例。



但我需要的优先输出是显示item_code以及空值。

when i change the a.Item_code blank result will be displayed unless the item code is present in Item_M table which is a perfect example of query execution.

But the preffered output i need is to display the item_code along with the null values along with it.

推荐答案

您需要从保证记录存在的源获取item_code，或者您可以制作此类源。此外，您需要将过滤器移出where子句。

You need to get the item_code from a source where the record is guaranteed to exist or you can manufacture such a source. Furthermore you need to move the filters out of the where clause.

Select distinct a.Item_Name, b.Item_Rate, b.professional_Charge, c.discount, c.discount_Type, a.Dept_ID, c.Discount_Applicability
From (values ('ABS002')) as x(Item_code)
left outer join Item_M a on x.Item_code = a.Item_Code
left outer join Rate_M b on a.Item_Code = b.Bill_Item and b.Rate_Cat_ID = 'DLX'
left outer join Discount_M c on a.Item_Code = c.Item_Code and c.Pay_Type_Id='BD'

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