[英]C# DataView RowFilter, null value for DateTime column
I'm trying to filter on null columns (I only want to show rows where the column is null), but the issue is I can't compare the column to a null, since the column is of DateTime value. 我正在尝试过滤空列(我只想显示列为空的行),但问题是我无法将列与null进行比较,因为该列是DateTime值。
I get the following error 我收到以下错误
System.Data.EvaluateException: Cannot perform '=' operation on System.DateTime and System.String. System.Data.EvaluateException:无法对System.DateTime和System.String执行'='操作。
This is my code for the filter 这是我的过滤器代码
CourseID IN (" + courseIds + ") AND Isnull(DateBooked, 'Null Column') = 'Null Column'
DateBooked is the column with DateTime value. DateBooked是具有DateTime值的列。 Everything before the Isnull is functioning correctly. 在Isnull正常运作之前的一切。 Help please! 请帮助!
Doesn't isnull
always return a value of the same type as its first parameter? isnull
是否始终返回与其第一个参数相同类型的值?
Try DateBooked IS NULL
instead of Isnull(DateBooked, 'Null Column') = 'Null Column'
. 尝试DateBooked IS NULL
而不是Isnull(DateBooked, 'Null Column') = 'Null Column'
。
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