using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SQLTest
{
 class Program
 {
 static void Main(string[] args)
 {
 ///連接數據庫
 string connection =
 "server=潘尚\\SQLEXPRESS;database=db_test;Trusted_Connection=true";
 SqlConnection sc = new SqlConnection(connection);
 // sc.ConnectionString = connection;
 try
 {
 sc.Open(); //打開數據庫連接
 Console.WriteLine("已經打開數據庫連接!");
 SqlCommand cmd = new SqlCommand("SELECT * FROM db_student", sc);
 SqlDataReader sdr = cmd.ExecuteReader(); //執行查找記錄命令
 while(sdr.Read())
 {
 Console.WriteLine("{0}{1}{2}{3}", sdr[0], sdr[1], sdr[2], sdr[3]);
 }
//START:4.查詢數據庫記錄//////////////////////////////////////////////////////////////
 /* SqlCommand cmd = new SqlCommand("SELECT count(*) FROM db_student", sc);
 int i = (int)cmd.ExecuteScalar();//執行查找記錄的命令
 Console.WriteLine("表中共有{0}條數據", i.ToString()); */
//END:4.查詢數據庫記錄////////////////////////////////////////////////////////////////
//START:3.修改數據庫數據的代碼////////////////////////////////////////////////////////
 /* SqlCommand cmd = new SqlCommand("UPDATE db_student SET student_grade=99 where student_name=@name", sc); //創建SqlCommand對象
 cmd.Parameters.Add("@name", SqlDbType.VarChar).Value = "潘";
 int i = cmd.ExecuteNonQuery();
 if (i > 0) Console.WriteLine("修改成功!"); */
//END:3.修改數據庫數據的代碼/////////////////////////////////////////////////////////
//START:1.刪除數據庫記錄代碼段///////////////////////////////////////////////////////
 /* string cmdtext = "DELETE FROM db_student WHERE student_name=@name";
 SqlCommand cmd = new SqlCommand(cmdtext, sc);
 cmd.Parameters.Add("@name", SqlDbType.VarChar).Value = "潘";
 int i = cmd.ExecuteNonQuery();
 if (i > 0) Console.WriteLine("刪除記錄成功!"); */
//END:1.刪除數據庫記錄代碼段/////////////////////////////////////////////////////////
//START:2.添加記錄的代碼///////////////////////////////////////////////////////////////
 /* SqlCommand cmd = new SqlCommand();//創建SqlCommand對象
 cmd.CommandType = CommandType.Text; //設置執行文本命令
 cmd.Connection = sc; //設置對象屬性
 cmd.CommandText = 
 "INSERT INTO db_student(student_name,student_age,student_address,student_grade)VALUES(@name,@age,@address,@grade)";
 //添加參數并為參數賦值
 cmd.Parameters.Add("@name", SqlDbType.VarChar, 10).Value = "潘";
 cmd.Parameters.Add("@age", SqlDbType.Int).Value = 19;
 cmd.Parameters.Add("@address", SqlDbType.VarChar).Value = "武漢";
 cmd.Parameters.Add("@grade", SqlDbType.Int).Value = 100;
 int i = cmd.ExecuteNonQuery(); //執行數據庫添加記錄命令
 if (i > 0) Console.WriteLine("添加記錄成功"); */ //控制臺