转换表名（以字符串形式）以在LINQ查询中使用它：C＃，实体框架

Question

I have a list of table names in form of strings. I want to loop through the list and use the table name in the LINQ query:

var db = new SomeContext();

// for a single table I can use the LINQ query as
var res = from q in db.Table
          where ......
          select q;

and it works just fine.

The above approach is hard coding. I need a generic solution for this to loop through multiple tables whose names are stored in a list.

// list of string containing table names
List<stringtableNames = [Get the table list from some source]
// not a problem here

loop through the table names and for each name execute a LINQ query as shown below

foreach(string table in tableNames)
{ 
    var queryRes = from t in table
                   where <some_condition>
                   select t; 
}

In the above statements "from t in table" above is not valid as "table" is a string. I need actual table object reference to use.

Need help on how do I go about doing that.

Answer 1

You can use the DbContext.Set method:

Set(System.Type.GetType("TableName"))

Above sentence will return a non generic DbSet. So, you will not be able to query with linq as usual. But you can use dynamic linq. ScottGu will explain it better than me . Please, check this thread for other solutions.

Answer 2

select, where, from is one way to define LINQ but You can use it if you have a list of elements ( IEnumerable<T> for example), but You have only name of Your table

I think You have to create a regular SQL query

foreach(string table in tableNames)
{ 
  var query =$"select * from  {table} where <some_condition>"; 
  var list = db.ExecuteStoreQuery<Obj>(query);
}

In EF You can execute regular query

Answer 3

In EF you can execute SQL Code .

In this example i use EF with SQL ( String )

var db = new SomeContext();
var list = db.ExecuteStoreQuery<Obj>(Obj.sql);



class Obj
{
   public const string sql = @"select [tbl].[field] from [tbl]";
}