在C#中选择linq中的case

Question

我怎样才能将以下sql语句转换为linq

 select  AdsProperties.AdsProID,
         AdsProperties.IsActive,
         AdsProperties.Name,
           case
                when AdsProperties.ControlType =1 then -- TextBox
                  'Textbox'
                when AdsProperties.ControlType =2 then -- DropDown
                  'Dropdown'
                when AdsProperties.ControlType =3 then -- ConboBox
                  'ComboBox'
                else -- RadioButton
                  'RadioButtont'
           end as ControlType   
   from CLF.utblCLFAdsPropertiesMaster as AdsProperties

我试过这个

var query = from AdsProperties in db.utblCLFAdsPropertiesMasters
            select new
            {
                AdsProperties.AdsProID,
                AdsProperties.Name,
                AdsProperties.IsActive,
                ControlType = AdsProperties.ControlType == 1 ? (int?)"TextBox" : null,
                ControlType = AdsProperties.ControlType == 2 ? (int?)"Dropdown" : null,
                ControlType = AdsProperties.ControlType == 3 ? (int?)"ComboBox" : null,                 
                ControlType = AdsProperties.ControlType == 4 ? (int?)"RadioButton" : null)
            };
            dt = query.CopyToDataTableExt();

但是我收到了这个错误

`an anynomous type cannot have multiple properties with the same name`

我知道这可能很简单.然而,作为linq的新人,我没有处理它的approrpiate经验.任何帮助,将不胜感激.提前致谢.

Answer 1

将字符串数组声明为：

string[] controls = new string[] {"TextBox","Dropdown","ComboBox","RadioButton"};

如下所述修改您的查询：

var query = from AdsProperties in db.utblCLFAdsPropertiesMasters
                    select new
                    {
                        AdsProperties.AdsProID,
                        AdsProperties.Name,
                        AdsProperties.IsActive,
                        ControlType = AdsProperties.ControlType < controls.Length ? controls[AdsProperties.ControlType-1] : null
                    };
        dt = query.CopyToDataTableExt();