数据库操作 连接 增删改查 断开

传统方式

将数据库操作封装成一个工具类

using System.Data;
using System.Data.SqlClient;
public class TraditionalSQLServerDBManager
{
    SqlConnection con;
    public TraditionalSQLServerDBManager()
    {
        con = new SqlConnection();
        con.ConnectionString = "Server=;DataBase=;Uid=;pwd=;";
        con.Open();
     }

    public void ExcuteSQL(string sql)
    {
        SqlCommand com = new SqlCommand();
        com.Connection = con;
        com.CommandType = CommandType.Text;
        com.CommandText = sql;
        SqlDataReader dr = com.ExecuteReader();//执行SQL语句
        dr.Close();//关闭执行
        con.Close();//关闭数据库
     }
}

使用工具类

TraditionalSQLServerDBManager manager = new TraditionalSQLServerDBManager();
manager.ExcuteSQL(@"INSERT INTO [test2].[dbo].[BitTable] ([IsDelete]) VALUES(1)");

使用第三方库Dapper

封装工具类

public class DbManager<T> where T : class
{
    private static DbManager<T> instance;
    private static object _lock = new object();
    private SqlConnection connection;
    public static DbManager<T> Instance
    {
        get
        {
            lock (_lock)
            {
                if (instance == null)
                {
                    instance = new DbManager<T>();
                }
             }
            return instance;
        }
    }

    public DbManager()
    {
        connection = new SqlConnection("Server=;DataBase=;Uid=;pwd=;");
        connection.Open();
    }

    public IEnumerable<T> QueryBySQL(string sql)
    {
        return connection.Query<T>(sql);
    }

    public bool ExecuteOne(string sql)
    {
        if (connection.Execute(sql) != 0)
            return true;
        return false;
    }
}

调用方法

List<BitModel> list = new BLL.AboutDBManager().GetBitModel();

连接其他数据库，引用目标数据库相关DLL，将SqlConnection改为目标Connection即可。
如：

using System.Data.SQLite;
private SQLiteConnection connection;

其他

多个不同的数据库连接，比如MySQL,SQL Server,Oracle等，可以考虑采用接口实现多态