“等于”方法不支持

Question

public List<Health_Scheme_System.Employee> GetPenEmployeeTable()
{   
    Health_Scheme_System.Health_Scheme_SystemDB db = new Health_Scheme_System.Health_Scheme_SystemDB();

    var x = (from c in db.Employees
             where c.Pensioners.Equals (1) 
             select c); 

    return x.ToList();
}   

//Selecting multiple columns from an HR view table together with the scheme name of scheme.
public List<EmployeesX> GetPensioners()
{   
    Health_Scheme_System.Health_Scheme_SystemDB db = new Health_Scheme_System.Health_Scheme_SystemDB();

    List<Health_Scheme_System.EmployeeDirectory> listEmployeeView = GetPenEmployeeView();
    List<Health_Scheme_System.Employee> listEmployeeTable = GetPenEmployeeTable();
    List<Health_Scheme_System.Scheme> listSchemes = GetSchemes();

    List<EmployeesX> listOfEmployees = new List<EmployeesX>();

    //checking for comparision of getemployeeview to getemployee table and then to getschemes
    //Then display the scheme name if they are similar.
    for (int i = 0; i < listEmployeeView.Count; i++)
    {   
        EmployeesX emp = new EmployeesX();
        emp.ID_NO = listEmployeeView[i].ID_NO;
        emp.FIRST_NAME = listEmployeeView[i].FIRST_NAME;
        emp.LAST_NAME = listEmployeeView[i].LAST_NAME;
        emp.LOCATION_CODE = listEmployeeView[i].LOCATION_CODE;

        for (int j = 0; j < listEmployeeTable.Count; j++)
        {   
            if (listEmployeeTable[j].EmployeeIDCard == listEmployeeView[i].ID_NO)
            {   
                emp.Pensioners = listEmployeeTable[j].Pensioners;

                    for (int k = 0; k < listSchemes.Count; k++)
                    {   
                        if (listEmployeeTable[j].SchemeID == listSchemes[k].SchemeID)
                        {   
                            emp.SCHEME_NAME = listSchemes[k].Name;
                            emp.START_DATE = listEmployeeTable[j].StartSchemeDate;
                        }   
                    }   
            }   
        }   
        listOfEmployees.Add(emp);
    }   
    return listOfEmployees;
}   

如何使用 .equals 做出相同的方法？

Answer 1

您是否尝试过此操作：

var x = (from c in db.Employees
         where c.Pensioners == 1
         select c)

附加信息：

如果您在 linq 查询中的对象上使用方法，亚音速需要知道如何将其转换为 pur SQL 代码。默认情况下这不起作用，并且必须为每个数据提供程序的每个受支持类型上的每个已知方法实现（如果与默认实现不同）。因此，亚音速还有很多工作要做。

了解支持什么和不支持什么的一个很好的起点是 TSqlFormatter 类。看看protected override Expression VisitMethodCall(MethodCallExpression m)

https://github.com/subsonic/SubSonic-3.0/blob/master/SubSonic.Core/Linq/Structure/TSqlFormatter.cs

已经有一个 Equals< 的实现/code>

        else if (m.Method.Name == "Equals")
        {
            if (m.Method.IsStatic && m.Method.DeclaringType == typeof(object))
            {
                sb.Append("(");
                this.Visit(m.Arguments[0]);
                sb.Append(" = ");
                this.Visit(m.Arguments[1]);
                sb.Append(")");
                return m;
            }
            else if (!m.Method.IsStatic && m.Arguments.Count == 1 && m.Arguments[0].Type == m.Object.Type)
            {
                sb.Append("(");
                this.Visit(m.Object);
                sb.Append(" = ");
                this.Visit(m.Arguments[0]);
                sb.Append(")");
                return m;
            }
            else if (m.Method.IsStatic && m.Method.DeclaringType == typeof(string))
            {
                //Note: Not sure if this is best solution for fixing side issue with Issue #66
                sb.Append("(");
                this.Visit(m.Arguments[0]);
                sb.Append(" = ");
                this.Visit(m.Arguments[1]);
                sb.Append(")");
                return m;
            }
        }

我想 Prnsioners 是一个整数类型，所以你基本上必须添加另一个 else if 并重新编译亚音速。

这应该有效，但我还没有测试过。

            else if (!m.Method.IsStatic && m.Method.DeclaringType == typeof(int))
            {
                sb.Append("(");
                this.Visit(m.Arguments[0]);
                sb.Append(" = ");
                this.Visit(m.Arguments[1]);
                sb.Append(")");
                return m;
            }

（或者您可以尝试使用 == 方法，如顶部的示例所示）。