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如何编写C代码以删除SQL数据库中的数据？

admin
行业动态
2025-03-04
4

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csharp，using (SqlConnection conn = new SqlConnection("your_connection_string"))，{， conn.Open();， string query = "DELETE FROM TableName WHERE Condition";， SqlCommand cmd = new SqlCommand(query, conn);， int rowsAffected = cmd.ExecuteNonQuery();，}，

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C# 删除 SQL 数据库代码编写指南

在C#中，要删除SQL数据库中的记录或表，通常需要使用ADO.NET或Entity Framework等数据访问技术，下面将详细介绍如何使用这两种方法来删除数据库中的记录和表。

使用 ADO.NET 删除记录

步骤：

1、引入命名空间

   using System;
   using System.Data;
   using System.Data.SqlClient;

2、建立数据库连接

   string connectionString = "Server=myServerAddress;Database=myDataBase;User Id=myUsername;Password=myPassword;";
   using (SqlConnection connection = new SqlConnection(connectionString))
   {
       connection.Open();
       // 后续操作...
   }

3、创建并执行删除命令

   string sql = "DELETE FROM TableName WHERE Condition";
   using (SqlCommand command = new SqlCommand(sql, connection))
   {
       int rowsAffected = command.ExecuteNonQuery();
       Console.WriteLine($"Rows Affected: {rowsAffected}");
   }

示例代码：

using System;
using System.Data;
using System.Data.SqlClient;
class Program
{
    static void Main()
    {
        string connectionString = "Server=myServerAddress;Database=myDataBase;User Id=myUsername;Password=myPassword;";
        string deleteSQL = "DELETE FROM Employees WHERE EmployeeID = @EmployeeID";
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();
            using (SqlCommand command = new SqlCommand(deleteSQL, connection))
            {
                command.Parameters.AddWithValue("@EmployeeID", 1);
                int rowsAffected = command.ExecuteNonQuery();
                Console.WriteLine($"Rows Affected: {rowsAffected}");
            }
        }
    }
}

2. 使用 Entity Framework 删除记录

步骤：

1、安装Entity Framework包

通过NuGet包管理器安装EntityFramework。

2、定义数据模型

   public class Employee
   {
       public int EmployeeID { get; set; }
       public string Name { get; set; }
       // 其他属性...
   }

3、配置DbContext

   public class MyDbContext : DbContext
   {
       public DbSet<Employee> Employees { get; set; }
       protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
       {
           optionsBuilder.UseSqlServer("Server=myServerAddress;Database=myDataBase;User Id=myUsername;Password=myPassword;");
       }
   }

4、删除记录

   using (var context = new MyDbContext())
   {
       var employee = context.Employees.Find(1); // 根据主键查找记录
       if (employee != null)
       {
           context.Employees.Remove(employee);
           context.SaveChanges();
           Console.WriteLine("Record deleted successfully.");
       }
       else
       {
           Console.WriteLine("Record not found.");
       }
   }

示例代码：

using System;
using System.Linq;
using Microsoft.EntityFrameworkCore;
class Program
{
    static void Main()
    {
        using (var context = new MyDbContext())
        {
            var employee = context.Employees.Find(1); // 根据主键查找记录
            if (employee != null)
            {
                context.Employees.Remove(employee);
                context.SaveChanges();
                Console.WriteLine("Record deleted successfully.");
            }
            else
            {
                Console.WriteLine("Record not found.");
            }
        }
    }
}