C#&SQL Server基于三层架构实现增删改查

目录

框架一览

C#

SQL Server

C#程序编写

1_首先创建以下四个项目

2_Model实体模型搭建

3_DAL数据访问层

4_BLL业务逻辑层

5_UI表现层

UI全部代码

效果展示(视频)

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框架一览

先来看看C#和SQL Server的整个框架

C#

SQL Server

这是本次使用到数据库的一些信息

服务器名称：DESKTOP-D258CHD\WINCC

登录用户：sa     密码：123

数据库：Architecture_demo     表名：Student

清楚了框架那么现在开始编写C#部分的程序

C#程序编写

1_首先创建以下四个项目

BLL、DAL、Model为".dll类库"项目，UI为"Windows窗体应用程序"项目

2_Model实体模型搭建

创建Students类，且Students要为public

C#中的Students类与数据库中的Student的表，是多了一个“s”的，用于区分

这里的属性要与数据库中的Student表要一样

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;​namespace Model{    public class Students    {        public int student_ID { get; set; }        public string name { get; set; }        public int age { get; set; }        public string gender { get; set; }    }}

3_DAL数据访问层

首先在UI项目里的App.config文件中添加一段代码，在数据库服务器名称和密码发生改变时，不用修改程序代码，只需要修改App.config文件中这段代码既可

Server：数据库服务器的名称   DataBase：数据库名称

Uid：用户名  Pwd：密码

然后返回到DAL项目，在DAL项目引用里添加System.Configuration，用于读取UI项目的App.config文件

在DAL项目里创建SQLHelper类，SQLHelper要为public，同时引入System.Data、System.Data.SqlClient、System.Configuration

System.Data：提供对数据的操作

System.Data.SqlClient：提供对数据库的操作

System.Configuration：提供对App.config的操作

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;​using System.Data;using System.Data.SqlClient;using System.Configuration;​namespace DAL{    public class SQLHelper    {​    }}

开始编写数据访问层代码

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;​using System.Data;using System.Data.SqlClient;using System.Configuration;​namespace DAL{    public class SQLHelper    {        private static readonly string connString = ConfigurationManager.ConnectionStrings["connString"].ToString();​        /// 
        /// 对数据库进行增删改        /// 
        /// 要查询的SQL语句        /// 返回受影响的行数        public static int Update(string sql)        {            //与数据库连接的字符串            SqlConnection conn = new SqlConnection(connString);            //SQL语句            SqlCommand cmd = new SqlCommand(sql, conn);            try            {                //与数据库建立连接                conn.Open();                return cmd.ExecuteNonQuery();            }            catch (Exception ex)            {​                throw ex;            }            finally            {                //断开与数据库的连接                conn.Close();            }        }​​        /// 
        /// 执行单一结果查询        /// 
        /// 要查询的SQL语句        /// 返回单一的查询结果        public static object GetSingleResult(string sql)        {            SqlConnection conn = new SqlConnection(connString);            SqlCommand cmd = new SqlCommand(sql, conn);            try            {                conn.Open();                return cmd.ExecuteScalar();            }            catch (Exception ex)            {​                throw ex;            }            finally            {                conn.Close();            }        }​        /// 
        /// 执行一个结果集的查询        /// 
        /// 要查询的SQL语句        /// 返回一个SqlDataReader对象        public static SqlDataReader GetReader(string sql)        {            SqlConnection conn = new SqlConnection(connString);            SqlCommand cmd = new SqlCommand(sql, conn);            try            {                conn.Open();                SqlDataReader objReader = cmd.ExecuteReader(CommandBehavior.CloseConnection);                return objReader;            }            catch (Exception ex)            {​                throw ex;            }        }​​    }}​

4_BLL业务逻辑层

在BLL里创建StudentService类，StudentService要为public

引入DAL、Model

接着在StudentService类的代码里引入

System.Data、System.Data.SqlClient

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;​using System.Data;using System.Data.SqlClient;using DAL;using Model;​namespace BLL{    public class StudentService    {​    }}​

开始编写业务逻辑层代码

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;​using System.Data;using System.Data.SqlClient;using DAL;using Model;​namespace BLL{    public class StudentService    {​        /// 
        /// 增加一条数据        /// 
        ///         ///         public int AddStudent(Students objStudent)        {            //【1】编写sql语句            StringBuilder sqlBuilder = new StringBuilder("insert into Student ");            sqlBuilder.Append(" (name,age,gender) ");            sqlBuilder.Append(" values('{0}',{1},'{2}');select @@identity ");            //【2】解析对象            string sql = string.Format(sqlBuilder.ToString(), objStudent.name,objStudent.age,objStudent.gender);​            //【3】提交SQL语句            try            {                return Convert.ToInt32(SQLHelper.GetSingleResult(sql));//执行sql语句，返回学号            }            catch (Exception ex)            {                throw new Exception("添加学员时数据访问异常：" + ex.Message);            }        }​        /// 
        /// 删除一条数据        /// 
        ///         ///         public int DeleteStudent(string studentId)        {            string sql = "delete from Student where Student_ID=" + studentId;            try            {                return SQLHelper.Update(sql);            }            catch (SqlException ex)            {                //547是数据库返回的消息，返回改该消息表示不能被删除                if (ex.Number == 547)                {                    throw new Exception("该学号被其他实体引用，不能直接删除该学员对象！");                }                else                {                    throw new Exception("删除学员对象发生数据异常！" + ex.Message);                }            }            catch (Exception ex)            {                throw ex;            }        }​​        /// 
        /// 修改学生信息        /// 
        ///         ///         public int ModifyStudent(Students objStudent)        {            StringBuilder sqlBuilder = new StringBuilder();            sqlBuilder.Append("update Student set name='{0}',age={1},gender='{2}'  ");            string sql = string.Format(sqlBuilder.ToString(), objStudent.name,objStudent.age,objStudent.gender);            try            {                return SQLHelper.Update(sql);            }            catch (Exception ex)            {                throw new Exception("修改学员信息是数据访问发生异常：" + ex.Message);            }        }​        /// 
        /// 根据学号查询学生        /// 
        ///         ///         public Students GetStudentById(string studentId)        {            string sql = "select Student_ID,name,age,gender from Student ";            sql += " where Student_ID=" + studentId;            SqlDataReader objReader = SQLHelper.GetReader(sql);            Students objStudent = null;            if (objReader.Read())            {                objStudent = new Students()                {                    student_ID=Convert.ToInt32(objReader["student_ID"]),                    name=objReader["name"].ToString(),                    age = Convert.ToInt32(objReader["age"]),                    gender=objReader["gender"].ToString()                };            }            objReader.Close();            return objStudent;        }​    }}​

5_UI表现层

在工具箱找到TabControl，拖动到窗口

增加两个页面，第一个为“增”，第二个为“删、改、查”，并且修改界面

“增”界面

这里说明一下因为学号在数据库里面是主键，是不能更改的，但是在添加其他数据的时候，学号是会自增数据的，每一条数据+1，这个每次增加的数可以在数据库里面修改的

“删、改、查”界面

引入DAL、BLL、Model

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;​using DAL;using BLL;using Model;​namespace UI{    public partial class Form1 : Form    {        public Form1()        {            InitializeComponent();        }​    }}​

开始编写UI表现层代码

“增”界面代码

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;​using DAL;using BLL;using Model;​namespace UI{    public partial class Form1 : Form    {        private StudentService objStudentService = new StudentService();        List stuList = new List();//用来临时保存学员对象​        public Form1()        {            InitializeComponent();        }​​        /// 
        /// 添加按钮        /// 
        ///         ///         private void btn_Add_Click(object sender, EventArgs e)        {            //封装学生对象            Students ojbStudent = new Students()            {                name = this.txt_Z_name.Text.Trim(),                age = Convert.ToInt32(this.txt_Z_age.Text.Trim()),                gender = this.rdoMale.Checked ? "男" : "女"            };​            //调用后台数据访问方法            int studentId = objStudentService.AddStudent(ojbStudent);​            try            {                    //同步显示添加的学员                    ojbStudent.student_ID = studentId;                    this.stuList.Add(ojbStudent);                    this.dgvStudentList.DataSource = null;                    this.dgvStudentList.DataSource = this.stuList;​                //询问是否继续添加                DialogResult result = MessageBox.Show("新学员添加成功！是否继续添加？", "提示信息", MessageBoxButtons.YesNo, MessageBoxIcon.Question);​                if (result == DialogResult.Yes)                {                    //清空用户输入的信息                    foreach (Control item in this.gbstuinfo.Controls)                    {                        if (item is TextBox)                        {                            item.Text = "";                        }                        else if (item is RadioButton)                        {                            ((RadioButton)item).Checked = false;                        }                    }                }​            }            catch (Exception ex)            {                MessageBox.Show("添加学员出现数据访问异常" + ex.Message);            }​​​        }​    }}​

UI全部代码

“删、改、查”界面代码，和“增”界面的一起，这里就是UI全部的代码

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;​using DAL;using BLL;using Model;​namespace UI{    public partial class Form1 : Form    {        private StudentService objStudentService = new StudentService();        List stuList = new List();//用来临时保存学员对象​        public Form1()        {            InitializeComponent();        }​​        /// 
        /// 添加按钮        /// 
        ///         ///         private void btn_Add_Click(object sender, EventArgs e)        {            //封装学生对象            Students ojbStudent = new Students()            {                name = this.txt_Z_name.Text.Trim(),                age = Convert.ToInt32(this.txt_Z_age.Text.Trim()),                gender = this.rdoMale.Checked ? "男" : "女"            };​            //调用后台数据访问方法            int studentId = objStudentService.AddStudent(ojbStudent);​            try            {                    //同步显示添加的学员                    ojbStudent.student_ID = studentId;                    this.stuList.Add(ojbStudent);                    this.dgvStudentList.DataSource = null;                    this.dgvStudentList.DataSource = this.stuList;​                //询问是否继续添加                DialogResult result = MessageBox.Show("新学员添加成功！是否继续添加？", "提示信息", MessageBoxButtons.YesNo, MessageBoxIcon.Question);​                if (result == DialogResult.Yes)                {                    //清空用户输入的信息                    foreach (Control item in this.gbstuinfo.Controls)                    {                        if (item is TextBox)                        {                            item.Text = "";                        }                        else if (item is RadioButton)                        {                            ((RadioButton)item).Checked = false;                        }                    }                }​            }            catch (Exception ex)            {                MessageBox.Show("添加学员出现数据访问异常" + ex.Message);            }​​​        }​        /// 
        /// 查询按钮        /// 
        ///         ///         private void btn_Inquire_Click(object sender, EventArgs e)        {            if (this.txt_S_StudentId.Text.Length == 0)            {                MessageBox.Show("请输入学号！", "查询提示！");                return;            }            Students objStudent = objStudentService.GetStudentById(this.txt_S_StudentId.Text.Trim());            this.stuList.Add(objStudent);            this.dgvStudentList2.DataSource = null;            this.dgvStudentList2.DataSource = this.stuList;        }​​        /// 
        /// 修改按钮        /// 
        ///         ///         private void btn_Edit_Click(object sender, EventArgs e)        {            if (txt_S_Id.Text == ""||txt_S_name.Text==""||txt_S_age.Text==""||rdo_S_Male.Checked==false&&rdo_S_Female.Checked==false)            {                MessageBox.Show("数据不完整", "提示！");                return;            }            //封装学员对象            Students objStudent = new Students()            {                student_ID=Convert.ToInt32(this.txt_S_Id.Text.Trim()),                name = this.txt_S_name.Text.Trim(),                age=Convert.ToInt32(this.txt_S_age.Text.Trim()),                gender=this.rdoMale.Checked ? "男" : "女"            };​            try            {                if (objStudentService.ModifyStudent(objStudent) == 1)                {                    MessageBox.Show("学员信息修改成功！", "提示信息");                }            }            catch (Exception ex)            {                MessageBox.Show(ex.Message, "提示信息");            }​​        }​        private void dgvStudentList2_CellClick(object sender, DataGridViewCellEventArgs e)        {            txt_S_Id.Text= this.dgvStudentList2.CurrentRow.Cells["Student_ID"].Value.ToString();            txt_S_name.Text = this.dgvStudentList2.CurrentRow.Cells["name"].Value.ToString();            txt_S_age.Text = this.dgvStudentList2.CurrentRow.Cells["age"].Value.ToString();            if (this.dgvStudentList2.CurrentRow.Cells["gender"].Value.ToString() == "男")            {                rdo_S_Male.Checked = true;            }            else            {                rdo_S_Female.Checked = true;            }        }​        private void btn_Delete_Click(object sender, EventArgs e)        {​            if (this.dgvStudentList2.RowCount == 0)            {                MessageBox.Show("没有任何需要删除的学员！", "提示信息");                return;            }            if (this.dgvStudentList2.CurrentRow == null)            {                MessageBox.Show("请先选中要删除的学员！", "提示信息");                return;            }​            //删除前的确认            DialogResult result = MessageBox.Show("确认删除吗！", "提示信息", MessageBoxButtons.OKCancel, MessageBoxIcon.Question);            if (result == DialogResult.Cancel) return;​            //获取学号            string studentId = this.dgvStudentList2.CurrentRow.Cells["Student_ID"].Value.ToString();            try            {                objStudentService.DeleteStudent(studentId);                dgvStudentList2.DataSource = null;            }            catch (Exception ex)            {​                MessageBox.Show(ex.Message, "提示信息");            }​​        }    }}​

提示：表格的名字和数据名要与数据库的字段对应

效果展示(视频)

C#&SQL Server基于三层架构实现增删改查