使用DateTime列设置LinqDataSource Where子句

In C#.net, I have the following DataSource setup that I am trying to dynamically assign a WHERE clause to in the code behind...

在C#.net中,我有以下DataSource设置,我试图在后面的代码中动态分配WHERE子句...

<asp:LinqDataSource ID="LinqDataSource1" runat="server" 
     ContextTypeName="MyNameSpace.DataClasses1DataContext"
     TableName="MyTableWithADateTimeColumn" >
</asp:LinqDataSource>

The code behind looks something like this...

背后的代码看起来像这样......

LinqDataSource1.Where = "MyDateColumn == DateTime(" + DateTime.Now + ")";

This gives me an error of ')' or ',' expected. I've also tried casting it inside quotation marks, as well, as without casting it as DateTime and with quotation marks...

这给了我一个错误')'或','预期。我也试过把它放在引号内,因为没有把它作为DateTime和引号标记......

LinqDataSource1.Where = @"MyDateColumn == """ + DateTime.Now + @""" ";

This gives me Operator '==' incompatible with operand types 'DateTime' and 'String'. I've tried several other ways, but I am obviously missing something here.

这使得运算符'=='与操作数类型'DateTime'和'String'不兼容。我已经尝试了其他几种方法,但我显然在这里遗漏了一些东西。

Similar code is working fine for strings.

类似的代码适用于字符串。

6 个解决方案

#1

is it this? What about this then...

是这个吗?那么那......

LinqDataSource1.Where = "MyDateColumn == DateTime.Parse(" + DateTime.Now + ")"; 
//can't create a date from string in constructor use .Parse()...

#2

I believe you need to include double quotes around the string being converted to a DateTime.

我相信你需要在被转换为DateTime的字符串周围加上双引号。

LinqDataSource1.Where = "MyDateColumn == DateTime(\"" + DateTime.Now.ToString() + "\")";

#3

LinqDataSource1.Where = "MyDateColumn == Convert.ToDateTime(\"" + DateTime.Now + "\")";

LinqDataSource1.Where =“MyDateColumn == Convert.ToDateTime(\”“+ DateTime.Now +”\“)”;

#4

It's simple and straight forward:

这很简单直接:

Look in the page source of "asp:LinqDataSource" and add that clause in the "where" section.

查看“asp:LinqDataSource”的页面源代码,并在“where”部分添加该子句。

Adding this through the wizard with a NULL parameter fails.

通过向导使用NULL参数添加此操作失败。

Here is an example:

这是一个例子:

<asp:LinqDataSource ID="LinqDataSource1" runat="server" ContextTypeName="MyDataContext"
    EntityTypeName="" GroupBy="MyItem" Select="new (key as Item1, Count() as TotalQuantity)"
    TableName="MyTable" 

    Where="Country == @Country &amp;&amp; DateProcessed == NULL">
    <WhereParameters>
        <asp:ControlParameter ControlID="ddlCountry" DefaultValue="US" 
            Name="Country" PropertyName="SelectedValue" Type="String" />
    </WhereParameters>
</asp:LinqDataSource>

#5

So the final solution as suggested by J.13.L looked like this...

所以J.13.L建议的最终解决方案看起来像这样......

LinqDataSource1.Where = @"MyDateColumn == DateTime.Parse(""" + MyDateTime + @""") ";

But since I didn't want to match on the time part of the date it really looked more like this...

但由于我不想在日期的时间部分匹配,它看起来更像是......

LinqDataSource1.Where = @"MyDateColumn >= DateTime.Parse(""" + MyDateTime + @""") AND MyDateColumn < DateTime.Parse(""" + MyDateTime.AddDays(1) + @""")";

#6

Another programmatically way:

另一种编程方式:

dataSource.WherePredicateParameters.Clear();
OrExpressionParameter expression = new OrExpressionParameter();
expression.Parameters.Add("Birthday", DbType.DateTime, Convert.ToDateTime(txtBirthday.Text).ToString());
dataSource.WherePredicateParameters.Add(expression);

#1