C# 连接数据库（添加，修改，删除）

叁歲伎倆 2024-02-17 16:54 47阅读 0赞

一、添加年级信息到表中

/// <summary>
            /// 添加年级表
            /// INSERT INTO grade VALUES('IT11')
            /// </summary>
            private static void addGrade(string gname)
            {
                SqlConnection con = null;
                try
                {
                    //1.连接字符串
                    string str = "Data Source=.;Initial Catalog=MySchool;Integrated Security=True";
    
                    //2.连接对象
                    con = new SqlConnection(str);
    
                    //3.打开连接
                    con.Open();
    
                    //4.sql语句
                    //INSERT INTO grade VALUES('IT11')
                    StringBuilder bulider = new StringBuilder();
                    bulider.AppendLine("INSERT");
                    bulider.AppendLine(" INTO ");
                    bulider.AppendLine(" grade ");
                    bulider.AppendLine(" VALUES ");
                    bulider.AppendFormat("('{0}') ", gname);
                    // Console.WriteLine(bulider.ToString());
    
                    //5.命名对象
                    SqlCommand cmd = new SqlCommand(bulider.ToString(), con);
    
                    //6.执行sql语句 返回Int
                    int count = cmd.ExecuteNonQuery();
    
                  // Console.WriteLine(count);
    
                    if (count > 0)
                    {
                        Console.WriteLine("OK!");
                    }
                    else
                    {
                        Console.WriteLine("no!");
                    }
                    
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.ToString());
                }
                finally
                {
                    con.Close();
                }
    
            }

二、修改学生的信息

/// <summary>
            /// 修改学生表
            /// UPDATE stu SET BornDate='1992-1-1',Phone='80011011' WHERE StudentName='白燕'
            /// </summary>
            private static void updateStudent(string date,string tel,string name)
            {
                SqlConnection con = null;
                try
                {
                    //1.连接字符串
                    string str = "Data Source=.;Initial Catalog=MySchool;Integrated Security=True";
    
                    //2.连接对象
                    con = new SqlConnection(str);
    
                    //3.打开连接
                    con.Open();
    
                    //4.sql语句
                    //UPDATE stu SET BornDate='1992-1-1',Phone='80011011' WHERE StudentName='白燕'
                    StringBuilder bulider = new StringBuilder();
                    bulider.AppendLine("UPDATE");
                    bulider.AppendLine(" stu ");
                    bulider.AppendLine(" SET ");
                    bulider.AppendFormat("  BornDate='{0}',Phone='{1}' ",date,tel);
                    bulider.AppendLine(" WHERE ");
                    bulider.AppendFormat("StudentName='{0}' ", name);
                    // Console.WriteLine(bulider.ToString());
    
                    //5.命名对象
                    SqlCommand cmd = new SqlCommand(bulider.ToString(), con);
    
                    //6.执行sql语句 返回Int
                    int count = cmd.ExecuteNonQuery();
    
                    // Console.WriteLine(count);
    
                    if (count > 0)
                    {
                        Console.WriteLine("OK!");
                    }
                    else
                    {
                        Console.WriteLine("no!");
                    }
    
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.ToString());
                }
                finally
                {
                    con.Close();
                }
    
            }

三、删除学生信息

/// <summary>
            /// 删除学生表
            /// delete stu WHERE StudentName='白燕'
            /// </summary>
            private static void delStudent(string name)
            {
                SqlConnection con = null;
                try
                {
                    //1.连接字符串
                    string str = "Data Source=.;Initial Catalog=MySchool;Integrated Security=True";
    
                    //2.连接对象
                    con = new SqlConnection(str);
    
                    //3.打开连接
                    con.Open();
    
                    //4.sql语句
                    // delete stu WHERE StudentName='白燕'
                    StringBuilder bulider = new StringBuilder();
                    bulider.AppendLine("delete");
                    bulider.AppendLine(" stu ");
                    bulider.AppendLine(" WHERE ");
                    bulider.AppendFormat("StudentName='{0}' ", name);
                    // Console.WriteLine(bulider.ToString());
    
                    //5.命名对象
                    SqlCommand cmd = new SqlCommand(bulider.ToString(), con);
    
                    //6.执行sql语句 返回Int
                    int count = cmd.ExecuteNonQuery();
    
                    // Console.WriteLine(count);
    
                    if (count > 0)
                    {
                        Console.WriteLine("OK!");
                    }
                    else
                    {
                        Console.WriteLine("no!");
                    }
    
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.ToString());
                }
                finally
                {
                    con.Close();
                }
    
            }

四、总结

操作添加，删除，修改数据，其实就是用SQLCommand命令对象中的ExecuteNonQuery（）来执行，返回是一个整数型的数据。