小编Mag*_*nus的帖子

我的私人获取所有方法

    private IQueryable<Category> getAll()
        => _unitOfWork.CategoryRepo
               .GetAll()
               .Include(x => x.CategoryDetails)
               .Include(x => x.Categories)
               .ThenInclude(x => x.CategoryDetails);

这是我尝试过的：

await getAll().OrderBy(x => x.Id).TakeLast(1000).ToListAsync()

错误（.net 6 和 3.1 中的错误相同）：

The LINQ expression 'DbSet<Category>()
    .Include(x => x.CategoryDetails)
    .Include(x => x.Categories)
    .ThenInclude(x => x.CategoryDetails)
    .OrderBy(x => x.Id)
    .TakeLast(__p_0)' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to 'AsEnumerable', 'AsAsyncEnumerable', 'ToList', or 'ToListAsync'. See https://go.microsoft.com/fwlink/?linkid=2101038 for more information.

我有这样的SQL查询:

SELECT Code 
FROM xyz 
WHERE xyz.Code  IN  ('20','10') AND price = 
    (select min(price) FROM xyz  WHERE CODE IN  ('20','10'));

查询后所需的输出:10

表xyz: -

价格:1 2 1

代码:10 20 30

有没有更好的方法来编写这个sql语句？因为在我的sql语句中"WHERE CODE IN('20','10')"重复两次,我试图避免两次调用此语句

这适用于SQL-Server 2008.这是一个示例列:

-----------------
|    strings    |
-----------------
|    string1    |
-----------------
|    string2    |
-----------------
|    string3    |
-----------------
|    string4    |
-----------------
|      ...      |
-----------------

什么是查询来计算不是"string1","string2"或"string3"的任何字符串的出现次数？

在C#中我有一个double数组(double[]我的意思是)我想将所有值四舍五入到C#中的两个小数位.

一个解决方案是使用foreach()和执行此Math.Round()功能,但数组非常大(1.000.000到10.000.000值)

而不是foreach,是否有更有效的解决方案？

我使用了始终为true的语句,例如1 = 1在MYSQL中使用where语句的case语句,语法如下:

select * from tablename where 
(case when tablefield is not null then 
 then tablefield = 'value'
else 1 = 1 end)

我想知道如何1 = 1在where子句中的sqlserver/tsql case语句中使用else (always true statement).

var orderedStudents = students.OrderBy(x => x.FacultyNumber).ToList();
var orderedWorkers = workers.OrderByDescending(x => x.moneyPerHour).ToList();

这些是我要合并的两个列表,但我无法弄清楚它们是如何具有不同类型的.

我有以下SQL语句：

select 
   p.productId, 
   p.minAge, 
   p.maxAge, 
   min(pcb.lowerbound) MinValue,    
   max(pcb.upperBound) MaxValue, 
   p.name ProductName
from gliweb..product p 
inner join gliweb..ProductClassBand pcb on pcb.productId = p.productId
where p.IncludeInQuote = 1
      and @currentAge between p.minAge and p.maxAge
group by p.productId, p.minAge, p.maxAge, p.name
order by p.name

如您所见，这是一个简单的语句，其中包含GROUP，然后是MIN / MAX。我正在尝试将此查询转换为C＃LINQ，但遇到了麻烦。

到目前为止，我有以下内容：

var productListDatabase = from products in DataContext.Products
    join band in DataContext.ProductClassBands on products.productId equals band.productId
    where products.minAge <= currentAge &&
            products.maxAge >= currentAge &&
            products.IncludeInQuote == true
    orderby products.name
            group products by new{
                products.productId,
                products.minAge …

用户表有

id, email, password, gender, dob 

等性别默认为null.我有另一张桌子user_gender,有first_name和gender.我的SQL查询获得来自用户User和选择性别User_Gender基础上first_name.用户表非常庞大,大约有300,000多行.我正在运行下面提到的查询,但这花费了太多时间.如何优化此查询？ -

select 
   count(*) 
from user u 
left outer join user_gender ug on ug.name = 
  case when locate(' ', u.name) > 0 then
     substring(u.name, 1,locate(' ', u.name))
  else
     u.name 
  end 
where 
  ug.gender != 'mf' and u.gender is null

如何设置CheckBox值,它位于Gridview内？

  <asp:GridView ID="gviewPermission" runat="server" 
        onrowdatabound="gviewPermission_RowDataBound" 
        onrowupdated="gviewPermission_RowUpdated" 
        onrowupdating="gviewPermission_RowUpdating">
        <Columns>
            <asp:TemplateField HeaderText="Allow" ItemStyle-HorizontalAlign="Center">
                <ItemTemplate>
                    <asp:CheckBox ID="Check_Allow" runat="server" />
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Deny" ItemStyle-HorizontalAlign="Center">
                <ItemTemplate>
                    <asp:CheckBox ID="Check_Deny" runat="server" />
                </ItemTemplate>
            </asp:TemplateField>
        </Columns>
    </asp:GridView>

复选框值必须根据某些条件设置....

我有一个班级名单 Test

public class Test
{
        public int Id { get; set; }
        public string Name { get; set; }
        public DateTime CreatedDate { get; set; }
        public DateTime? ModifiedDate { get; set; }
}

列表有以下数据

List<Test> lstTest = new List<Test>();
lstTest.Add(new Test() { Id = 1, Name = "Test 1", CreatedDate = Convert.ToDateTime("05/05/2005"), ModifiedDate = Convert.ToDateTime("09/05/2005") });
lstTest.Add(new Test() { Id = 2, Name = "Test 2", CreatedDate = Convert.ToDateTime("06/05/2005"), ModifiedDate = Convert.ToDateTime("07/05/2005") });
lstTest.Add(new Test() { Id = …