ADO.NET访问数据库方法总结

using System;
using System.Configuration;
using System.Data.SqlClient;
using MessageBoxer;

namespace ConnectDatabaseDemo
{
    /// <summary>
    ///     各种数据库连接字符串写法：https://www.connectionstrings.com/
    ///     LDH @ 2021-4-8
    ///     ADO.NET访问数据库方法总结
    /// </summary>
    internal class Program
    {
        private static void Main()
        {
            Console.Title = "使用ADO.NET连接数据库";

            //ConnectDbMethod01();

            ConnectDbMethod02();
        }

        /// <summary>
        ///     连接数据库方法1：将数据库连接字符串配置到App.config文件内,connectionStrings节点下
        /// </summary>
        private static void ConnectDbMethod01()
        {
            var conStr = ConfigurationManager.ConnectionStrings["ConnectionString"].ToString();
            var con = new SqlConnection(conStr);

            try
            {
                con.Open();
                ShowMessage.Notification("已打开数据库连接！", "温馨提示");
            }
            catch (Exception e)
            {
                ShowMessage.Error(e.Message, "异常提示");
            }
            finally
            {
                con.Close();
                ShowMessage.Notification("已关闭数据库连接！", "温馨提示");
            }
        }

        /// <summary>
        ///     连接数据库方法2：将数据库连接字符串配置到App.config文件内,appSettings节点下
        /// </summary>
        private static void ConnectDbMethod02()
        {
            var conStr = ConfigurationManager.AppSettings["ConnectionString"];
            using (var con = new SqlConnection(conStr))
            {
                try
                {
                    con.Open();
                    ShowMessage.Notification("已打开数据库连接！", "温馨提示");
                }
                catch (Exception e)
                {
                    ShowMessage.Error(e.Message, "异常提示");
                }
            }
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>

<configuration>
    <startup>
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.7.2" />
    </startup>
    <!--配置数据库连接字符串-->
    <connectionStrings>
        <!--写法1-->
        <add name="ConnectionString" connectionString="Data Source=localhost;Initial Catalog=TestDB;User Id=sa;Password=123456"/>
        <!--<add name="ConnectionString" connectionString="Data Source=.;Initial Catalog=TestDB;User Id=sa;Password=123456"/>-->
        <!--<add name="ConnectionString" connectionString="Data Source=127.0.0.1;Initial Catalog=TestDB;User Id=sa;Password=123456"/>-->
        <!--写法2-->
        <!--<add name="ConnectionString" connectionString="server=.;database=TestDB;uid=sa;pwd=123456"/>-->
        <!--<add name="ConnectionString" connectionString="server=localhost;database=TestDB;uid=sa;pwd=123456"/>-->
        <!--<add name="ConnectionString" connectionString="server=127.0.0.1;database=TestDB;uid=sa;pwd=123456" />-->
    </connectionStrings>
    <!--配置数据库连接字符串 方式1 ↑-->

    <!--配置数据库连接字符串-->
    <appSettings>
        <add key="ConnectionString" value="Data Source=localhost;Initial Catalog=TestDB;User Id=sa;Password=123456" />
    </appSettings>
    <!--配置数据库连接字符串 方式2 ↑-->
</configuration>

/*
    日期：2021-4-8
    人员：LDH
    说明：SQL-简单创建数据库和表
*/
IF EXISTS (SELECT * FROM sys.databases WHERE name = 'TestDB')
    DROP DATABASE TestDB;
GO

CREATE DATABASE TestDB;
GO

USE TestDB;
GO


CREATE TABLE Students
(
    Id INT IDENTITY(1, 1) PRIMARY KEY NOT NULL,
    Name NVARCHAR(20) NOT NULL,
    Age INT NOT NULL CHECK (Age
                            BETWEEN 1 AND 150
                           )
        DEFAULT 1,
    Address NVARCHAR(200) NOT NULL
        DEFAULT '地址不详'
);

INSERT INTO dbo.Students
(
    Name,
    Age,
    Address
)
VALUES
(   N'LDH', -- Name - nvarchar(20)
    32,     -- Age - int
    N'中国上海' -- Address - nvarchar(200)
    );

SELECT Id,
       Name,
       Age,
       Address
FROM dbo.Students;