在linq to sql查询中连接两个表

 ```csharp

 var query = from table1 in dataContext.Table1

             join table2 in dataContext.Table2 on table1.CommonField equals table2.CommonField

             select new

             {

                 // 选择需要返回的字段

             };

 ```

 ```csharp

 var query = from table1 in dataContext.Table1

             join table2 in dataContext.Table2 on table1.CommonField equals table2.CommonField into temp

             from t in temp.DefaultIfEmpty()

             select new

             {

                 // 选择需要返回的字段

             };

 ```

using System;
using System.Data.Linq;
using System.Linq;

namespace LinqToSqlExample
{
    // 创建自定义的数据上下文类
    public class DataContext : System.Data.Linq.DataContext
    {
        public Table<Table1> Table1;
        public Table<Table2> Table2;

        public DataContext(string connectionString) : base(connectionString) { }
    }

    // 定义实体类
    public class Table1
    {
        public int ID { get; set; }
        public string Name { get; set; }
        // 其他属性...
    }

    public class Table2
    {
        public int ID { get; set; }
        public string Description { get; set; }
        // 其他属性...
    }

    class Program
    {
        static void Main(string[] args)
        {
            // 创建数据上下文对象
            var connectionString = "your_connection_string";
            var dataContext = new DataContext(connectionString);

            // 执行连接查询
            var query = from table1 in dataContext.Table1
                        join table2 in dataContext.Table2 on table1.ID equals table2.ID
                        select new
                        {
                            table1.Name,
                            table2.Description
                        };

            // 执行查询并处理结果
            foreach (var result in query)
            {
                Console.WriteLine($"Name: {result.Name}, Description: {result.Description}");
            }
        }
    }
}