Question

sql列ReadershipLevels - int，带空

level是本地int类型变量

&是bitwise运营商

Linq to SQL

 vAdvanceSearchResults = from t 
                         in vAdvanceSearchResults 
                         where (t.ReadershipLevels & level) > 0 
                         select t;

如果level = 32

以上Linq查询生成了如下SQL：

SELECT [t2].[ReadershipLevels],[t2].[ID], [t2].[ISBN], [t2].[IsHighlighted], [t2].[Title], 
FROM (

    SELECT DISTINCT [t1].[ID], [t1].[ISBN], [t1].[IsHighlighted], [t1].[Title], [t1].[SuluAuthors], 
    FROM [dbo].[udf_SearchDWSearch]('swim', 'ALL') AS [t0]
    INNER JOIN [dbo].[DWSearch] AS [t1] ON [t0].[DWSearchID] = ([t1].[ID])
    WHERE [t1].[DatePublished] < '2016/05/27'
    ) AS [t2]
    WHERE ([t2].[ReadershipLevels] & 32) >0
    order by [t2].[ReadershipLevels]

我想要包含一个not所以我在下面做了

not ([t2].[ReadershipLevels] & 32) > 0



SELECT DISTINCT [t1].[ID], [t1].[ISBN], [t1].[IsHighlighted], [t1].[Title], [t1].[SuluAuthors], 
        FROM [dbo].[udf_SearchDWSearch]('swim', 'ALL') AS [t0]
        INNER JOIN [dbo].[DWSearch] AS [t1] ON [t0].[DWSearchID] = ([t1].[ID])
        WHERE [t1].[DatePublished] < '2016/05/27'
        ) AS [t2]
        WHERE not ([t2].[ReadershipLevels] & 32) >0
        order by [t2].[ReadershipLevels]

哪种方法正常。

现在我想在LINQ to SQL中也改变它

vAdvanceSearchResults = from t 
                        in vAdvanceSearchResults 
                        where ! (t.ReadershipLevels & level) > 0 
                        select t;

但是上面的投掷错误 - 不能适用于操作员！到System.Nullable类型的操作数

已更改为 -

vAdvanceSearchResults = from t 
                        in vAdvanceSearchResults 
                        where ! (t.ReadershipLevels.Value & level) > 0 
                        select t;

投掷错误 - 无法将操作符!应用于int类型的操作数

如何在!查询中添加LINQ运算符？

Answer 1

这对你有用。你不需要使用＆amp;操作

vAdvanceSearchResults = from t 
                        in vAdvanceSearchResults 
                        where t.ReadershipLevels.Value != level && t.ReadershipLevels.Value > 0 
                        select t;

Answer 2

尝试更改：where ! (t.ReadershipLevels.Value & level) > 0
对此：where ! ((t.ReadershipLevels.Value & level) > 0 )

Answer 3

为什么我们需要一个按位运算符？

如你的问题所述，如果你使用这个条件，

not ([t2].[ReadershipLevels] & 32) > 0

它将使用ReadershipLevels值检索所有结果（1至31），（64至95），（128至159）等等。

如果你真的想要显示上述范围内的记录，你可以使用如下not ([t2].[ReadershipLevels] & 32) > 0与检查它等于0相同，

vAdvanceSearchResults = from t 
                    in vAdvanceSearchResults 
                    where (t.ReadershipLevels.Value & level) == 0 
                    select t;

或者，如果您不想显示readerhiplevels值为“32”的记录，请执行简单的检查，

vAdvanceSearchResults = from t 
                    in vAdvanceSearchResults 
                    where (t.ReadershipLevels ?? 0) != 32 
                    select t;

希望有所帮助

Linq来sql！ int的类型为null的运算符

3 个答案: