ADO.NET
数据库连接
数据插入、删除、更改
数据查询
带单个参数
带多个参数
using MySql.Data.MySqlClient;
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace WpfTest
{
public class SqlHelper
{
private static string constr = ConfigurationManager.ConnectionStrings["db"].ConnectionString;
/// <summary>
/// 连接数据库
/// </summary>
/// <returns></returns>
public MySqlConnection? ConnectDatabase()
{
MySqlConnection connection = new MySqlConnection(constr);
connection.Open();
if (connection != null && connection.State == System.Data.ConnectionState.Open)
{
Console.WriteLine("数据库连接成功");
}
else
{
Console.WriteLine("数据库连接失败");
}
return connection;
}
/// <summary>
/// 关闭数据库
/// </summary>
/// <param name="mySqlConnection"></param>
public void CloseConnection(MySqlConnection mySqlConnection)
{
if (mySqlConnection != null && mySqlConnection.State == System.Data.ConnectionState.Open)
{
mySqlConnection.Close();
mySqlConnection = null!;
}
}/// <summary>
/// 执行数据DML(insert,update,delete)操作
/// </summary>
/// <param name="sql"></param>
public void ExecuteUpdate(string? sql)
{
var connection = ConnectDatabase();
MySqlCommand cmd = connection!.CreateCommand();
cmd.CommandText = sql;
int row = cmd.ExecuteNonQuery();
if (row > 0)
{
Console.WriteLine("操作成功");
}
else
{
Console.WriteLine("操作失败");
}
CloseConnection(connection);
}
/// <summary>
/// 数据查询的调用模板
/// </summary>
public void test()
{
MySqlParameter[] parameters = new MySqlParameter[]
{
new MySqlParameter("@height",30),
new MySqlParameter("@width",50),
};
string sql = "select * from tb_name where height=@height and width=@width";
ExecuteQuery(sql, parameters);
}
/// <summary>
/// 数据查询
/// </summary>
/// <param name="sql"></param>
public void ExecuteQuery(string sql, MySqlParameter[] mySqlParameters)
{
var connection = ConnectDatabase();
try
{
MySqlCommand mySqlCommand = new MySqlCommand(sql, connection);
foreach (MySqlParameter param in mySqlParameters)
{
mySqlCommand.Parameters.Add(param);
}
MySqlDataReader mySqlDataReader = mySqlCommand.ExecuteReader();
while (mySqlDataReader.Read())
{
mySqlDataReader.GetInt32(0); // 通过列的索引拿到数据
mySqlDataReader.GetString("表字段名1"); //通过列的名称拿到数据
mySqlDataReader.GetString("表字段名2");
}
mySqlDataReader.Close();
}
catch (Exception)
{
throw;
}
finally
{
CloseConnection(connection!);
}
}
}
}
基于特性+反射+DAO通用操作库
ORM对象关系映射
数据库中表映射为实体类
调用ORM框架中提供的新增方法：构建sql语句
创建枚举
根据枚举类型创建sql语句
调用
实体限定
生成参数列表
生成插入的所有方法
使用特性映射表名和字段名
通过特性获取真实的表名称
当字段名发生更改时会报错，所以给字段也添加特性
修改的方法
