在实体框架中使用Linq执行动态查询

Question

I have:

string table_name = "Orders";
string column_name = "Name";
string identity_column = "OrderID"
int identity_value = 5;

How can I achieve the following (dynamically):

var result = (from order in db.Orders
              where order.OrderId== identity_value 
              select order).SingleOrDefault();

For security reasons i cannot create a whole sql query and then execute it to server.

Answer 1

`System.Linq.Dynamic` library will help you generating dynamic query which has extension method

Where(string predicate,params object[] values)

To use this first include the namespace

using System.Linq.Dynamic;

then construct the predicate at run time

string predicate = "OrderId = @0";
int identity_value = 5;

then query db.Orders

db.Orders.AsQueryable().Where(predicate,identity_value);