C#连接数据库

VScode 配置C#环境 https://blog.csdn.net/qq_40346899/article/details/80955788

VScode 配置C#开发环境

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;using System.Data;
using System.Data.SqlClient;namespace ADODome
{class Program{static void Main(string[] args){string connString_1 = @"server=.\SQLEXPRESS;uid=sa;pwd=123456;database=Stu";SqlConnection conn = new SqlConnection(connString_1);conn.Open();if (ConnectionState.Open == conn.State){Console.WriteLine("Connection is Opend!");}conn.Close();if(ConnectionState.Closed == conn.State){Console.WriteLine("Connection is close!");}}}
}

封装类

class SqlHelp{private static string str = @"server=.\SQLEXPRESS;uid=sa;pwd=123456;database=Stu";public static object GetSingleResult(String sql){SqlConnection conn = new SqlConnection(str);SqlCommand cmd = new SqlCommand(sql, conn);conn.Open();object result = cmd.ExecuteScalar();conn.Close();return result;}public static int Update(String sql){SqlConnection conn = new SqlConnection(str);SqlCommand cmd = new SqlCommand(sql, conn);conn.Open();int result = cmd.ExecuteNonQuery();conn.Close();return result;}public static SqlDataReader GetReader(String sql){SqlConnection conn = new SqlConnection(str);SqlCommand cmd = new SqlCommand(sql, conn);conn.Open();//CommandBehavior.CloseConnection//不使用conn.close()SqlDataReader result = cmd.ExecuteReader(CommandBehavior.CloseConnection);           return result;}}

调用封装类 

public int AddStudent( string name){//"insert into student values('{0}');select @@identity";string sql = "insert into student values('{0}');select @@identity";sql = string.Format(sql, name);return SqlHelp.Update(sql);}public void GetStu(int age){string sql = "select * from student where age="+age;SqlDataReader reader =  SqlHelp.GetReader(sql);while (reader.Read()){Console.WriteLine("age:"+reader["age"] +";\tname:"+reader["name"]);}reader.Close();}