Question

我需要的简化示例：

表＆＃39;运输＆＃39;有2列; ＆＃39;车载＆＃39;和＆＃39;颜色＆＃39;。用户可以通过车辆，颜色或两者来过滤记录。

variable vehicle_choice = user_selected_vehicle (selected from a dropdown for example)
variable colour_choice = user_selected_colour

If user_selected_vehicle = nothing selected Then
    vehicle_choice = *
End if

If user_selected_colour = nothing selected Then
    colour_choice = *
End if

Select query = ("Select * From Transport Where Vehicle = vehicle_choice And Colour = colour_choice")

因此，如果用户想要一个红色＆＃39; ＆＃39;总线＆＃39;查询看起来像：

("Select * From Transport Where Vehicle = 'bus' And Colour = 'red'")

哪个会好的，如果它存在就找到记录。

但是，如果用户想要所有黄色的车辆，则查询看起来像：

("Select * From Transport Where Vehicle = * and Colour = 'yellow'")

显然，这一切都是用语法编写的，但这就是我想要的，是否可以在SQL中使用？（使用MS SQL Server 2008）

Answer 1

以下是解决此问题的两种典型方法。假设用户输入位于变量@vehicle和@colour：

中

where (vehicle = @vehicle or @vehicle is null) and
      (colour = @colour or @colour is null)

这种方法的问题是使用索引。索引策略很难用or。因此，如果要动态构建查询，那么最好只添加所需的子句：

@where = '1 = 1' +
         (case when @vehicle is not null then ' and vehicle = @vehicle' else '' end) +
         (case when @colour is not null then ' and colour = @colour' else '' end);

Answer 2

您可以准备第二个查询

("Select * From Transport Where Vehicle = * and Colour = 'yellow'")

到这个

("Select * From Transport Where Vehicle = Vehicle and Colour = 'yellow'")

只知道如何解决问题。

Answer 3

您可以尝试类似

的内容

("Select * From Transport Where Vehicle like '%' and Colour = 'yellow'")

Answer 4

是。它是可能的。只需修改你的查询：

假设您的下拉参数为：

ddl1.val -- for transport
ddl2.val -- for color

现在假设您的默认ddl值为“0”或“全部选择”选项。现在您的查询将是：

 Select * From Transport Where (Vehicle = ddl1.val or ddl1.val='0') and
(Colour = ddl2.val or ddl2.val='0')

替代方法：

Select * From Transport Where Vehicle like '%' and Colour = 'color_selected'

如果您对此有任何其他澄清，请告诉我。

Answer 5

declare @vehicle_choice nvarchar(255)
declare @colour_choice nvarchar(255)
set @colour_choice = 'bus'
set @colour_choice = 'blue'

Select * From Transport 
    where 1= 1 
    and Vehicle like (case when @vehicle_choice Is null or @vehicle_choice = '' then '%' else @vehicle_choice end)
    and Colour like (case when @colour_choice Is null or @colour_choice = '' then '%' else @colour_choice end)

从table中选择column = anything

5 个答案: