c# - Linq to Sql：如何快速清空表

Question

要删除表中的所有行，我目前正在执行以下操作：

context.Entities.DeleteAllOnSubmit(context.Entities);
context.SubmitChanges();

然而，这似乎需要很长时间。有更快的方法吗？

Answer 1

您可以使用DataContext.ExecuteCommand方法执行普通的 SQL 截断或删除命令：

context.ExecuteCommand("DELETE FROM Entity");

或者

context.ExecuteCommand("TRUNCATE TABLE Entity");

您删除的方式需要很长时间，因为 Linq to SQL 为每个实体生成一个 DELETE 语句，还有其他类型安全的方法可以进行批量删除/更新，请查看以下文章：

• 使用 LINQ to SQL 批量更新和删除
• LINQ to SQL 扩展：使用 Lambda 表达式批量删除

Answer 2

不幸的是，LINQ-to-SQL 不能很好地执行基于集合的查询。

你会假设

context.Entities.DeleteAllOnSubmit(context.Entities); 
context.SubmitChanges(); 

将转化为类似的东西

DELETE FROM [Entities]

但不幸的是它更像

DELETE FROM [dbo].[Entities] WHERE ([EntitiesId] = @p0) AND ([Column1] = @p1) ...
DELETE FROM [dbo].[Entities] WHERE ([EntitiesId] = @p0) AND ([Column1] = @p1) ...
DELETE FROM [dbo].[Entities] WHERE ([EntitiesId] = @p0) AND ([Column1] = @p1) ...

当您尝试在 LINQ-to-SQL 中进行批量更新时，您会发现同样的情况。一次超过几百行，这太慢了。

如果您需要执行批处理操作并且您正在使用 LINQ-to-SQL，则需要编写存储过程。

Answer 3

我喜欢使用扩展方法，根据以下内容：

public static class LinqExtension
{
  public static void Truncate<TEntity>(this Table<TEntity> table) where TEntity : class
  {
    var rowType = table.GetType().GetGenericArguments()[0];
    var tableName = table.Context.Mapping.GetTable(rowType).TableName;
    var sqlCommand = String.Format("TRUNCATE TABLE {0}", tableName);
    table.Context.ExecuteCommand(sqlCommand);
  }
}

Answer 4

你也可以使用这个：

Public void BorraFilasTabla()
{
 using(basededatos db = new basededatos())
 {
  var ListaParaBorrar = db.Tabla.Tolist();
  db.Tabla.RemoveRange(ListaParaBorrar); 
 }
}

Answer 5

下面的 c# 代码用于使用 LINQ to SQL 在数据库表上插入/更新/删除/删除全部

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;

namespace PracticeApp
{
    class PracticeApp
    {        
        public void InsertRecord(string Name, string Dept) {
            LinqToSQLDataContext LTDT = new LinqToSQLDataContext();
            LINQTOSQL0 L0 = new LINQTOSQL0 { NAME = Name, DEPARTMENT = Dept };
            LTDT.LINQTOSQL0s.InsertOnSubmit(L0);
            LTDT.SubmitChanges();
        }

        public void UpdateRecord(int ID, string Name, string Dept)
        {
            LinqToSQLDataContext LTDT = new LinqToSQLDataContext();
            LINQTOSQL0 L0 = (from item in LTDT.LINQTOSQL0s where item.ID == ID select item).FirstOrDefault();
            L0.NAME = Name;
            L0.DEPARTMENT = Dept;
            LTDT.SubmitChanges();
        }

        public void DeleteRecord(int ID)
        {
            LinqToSQLDataContext LTDT = new LinqToSQLDataContext();
            LINQTOSQL0 L0;
            if (ID != 0)
            {
                L0 = (from item in LTDT.LINQTOSQL0s where item.ID == ID select item).FirstOrDefault();
                LTDT.LINQTOSQL0s.DeleteOnSubmit(L0);
            }
            else
            {
                IEnumerable<LINQTOSQL0> Data = from item in LTDT.LINQTOSQL0s where item.ID !=0 select item;
                LTDT.LINQTOSQL0s.DeleteAllOnSubmit(Data);
            }           
            LTDT.SubmitChanges();
        }

        static void Main(string[] args) {
            Console.Write("* Enter Comma Separated Values to Insert Records\n* To Delete a Record Enter 'Delete' or To Update the Record Enter 'Update' Then Enter the Values\n* Dont Pass ID While Inserting Record.\n* To Delete All Records Pass 0 as Parameter for Delete.\n");
            var message = "Successfully Completed";
            try
            {
                PracticeApp pa = new PracticeApp();
                var enteredValue = Console.ReadLine();                
                if (Regex.Split(enteredValue, ",")[0] == "Delete") 
                {
                    Console.Write("Delete Operation in Progress...\n");
                    pa.DeleteRecord(Int32.Parse(Regex.Split(enteredValue, ",")[1]));
                }
                else if (Regex.Split(enteredValue, ",")[0] == "Update")
                {
                    Console.Write("Update Operation in Progress...\n");
                    pa.UpdateRecord(Int32.Parse(Regex.Split(enteredValue, ",")[1]), Regex.Split(enteredValue, ",")[2], Regex.Split(enteredValue, ",")[3]);
                }
                else
                {
                    Console.Write("Insert Operation in Progress...\n");
                    pa.InsertRecord(Regex.Split(enteredValue, ",")[0], Regex.Split(enteredValue, ",")[1]);
                }                                
            }
            catch (Exception ex)
            {
                message = ex.ToString();
            }
            Console.Write(message);            
            Console.ReadLine();                        
        }
    }
}