c# - 不存在从 ObjectParameter 到已知托管提供程序 native 类型的映射

Question

我正在使用 EF 为 Microsoft SQL Server 构建 WCF 服务，但不断收到以下错误:

Additional information: No mapping exists from object type System.Data.Objects.ObjectParameter to a known managed provider native type.

关于这个查询:

string ID = "XXID";
string Sql = @"SELECT * FROM @Table WHERE " + ID + " LIKE '@SearchTerm'";
ObjectParameter[] Parameters = new ObjectParameter[2];
Parameters[0] = new ObjectParameter("Table", Table);
Parameters[1] = new ObjectParameter("SearchTerm", SearchTerm);

using (var Context = new XXEntities())
{
    Context.Database.Connection.Open();
    IEnumerable<string> Query = Context.Database.SqlQuery<string>(Sql, Parameters);

    string[] Results = Query.ToArray();
    Context.Database.Connection.Close();
    return Results; 
}

我已经在 SQL Server 上测试了查询，它按预期工作 - 返回匹配 ID 的记录。

Answer 1

尝试使用sql参数代替对象参数

IEnumerable<string> Query = Context.Database.SqlQuery<string>(Sql, 
new SqlParameter("Table", Table), 
new SqlParameter("SearchTerm", SearchTerm));

理论上你可以在不需要像这样发送任何参数的情况下操作sql

IEnumerable<string> Query = Context.Database.SqlQuery<string>("SELECT * FROM "+Table+" WHERE " + ID + " LIKE '"+SearchTerm+"'");