ORM小练习代码
2018-06-18 02:49:51来源:未知 阅读 ()
DOG类
namespace RupengORM { public class Dog { public Dog() { } /// <summary> /// 显示提供无参构造函数 /// </summary> /// <param name="aa"></param> public Dog(int aa) { } public int Id { get; set; } public string Name { get; set; } public int Weight { set; get; } } }
Sqlhelper:
using System.Collections.Generic; using System.Configuration; using System.Data; using MySql.Data.MySqlClient; namespace RupengORM { public class DbSqlhelper { private static readonly string Sqlconnstr = ConfigurationManager.ConnectionStrings["mysqlconn"].ConnectionString; public static MySqlConnection CreateConnection() { MySqlConnection conn = new MySqlConnection(Sqlconnstr); conn.Open(); return conn; } public static int ExecuteNonQuery(MySqlConnection conn, string sql, params MySqlParameter[] parameters) { using (MySqlCommand cmd=conn.CreateCommand()) { cmd.CommandText = sql; cmd.Parameters.AddRange(parameters); return cmd.ExecuteNonQuery(); } } public static int ExecuteNonQuery(string sql, params MySqlParameter [] parameters) { using (MySqlConnection conn = CreateConnection()) { return ExecuteNonQuery(conn, sql, parameters); } } public static object ExecuteScalar(MySqlConnection conn, string sql, Dictionary<string, object> dictionary) { using (MySqlCommand cmd=conn.CreateCommand()) { cmd.CommandText = sql; foreach (var kvp in dictionary) { IDbDataParameter parameter = cmd.CreateParameter(); parameter.ParameterName = kvp.Key; parameter.Value = kvp.Value; cmd.Parameters.Add(parameter); } return cmd.ExecuteScalar(); } } public static object ExecuteScalar(string sql, Dictionary<string, object> dictionary) { using (MySqlConnection conn=CreateConnection()) { return ExecuteScalar(conn, sql, dictionary); } } public static DataTable ExecuteQuery(MySqlConnection conn, string sql, Dictionary<string, object> dictionary) { DataTable dataTable=new DataTable(); using (MySqlCommand cmd=conn.CreateCommand()) { cmd.CommandText = sql; foreach (var kvp in dictionary) { IDbDataParameter parameter = cmd.CreateParameter(); parameter.ParameterName = kvp.Key; parameter.Value = kvp.Value; cmd.Parameters.Add(parameter); using (IDataReader reader=cmd.ExecuteReader()) { dataTable.Load(reader); } } } return dataTable; } public static DataTable ExecuteQuery( string sql, Dictionary<string, object> dictionary) { using (MySqlConnection conn=CreateConnection()) { return ExecuteQuery(conn, sql, dictionary); } } } }
RProm 实现过程:
using System; using System.Collections.Generic; using System.Text; using MySql.Data.MySqlClient; namespace RupengORM { internal class RPorm { //约定:1、类名要和表名一样 //2、字段名和数据库列名一样 //3、主键的名字必须叫Id,必须是自动递增,int类型 // // // // // public static void Insert(object obj) { //获得obj对象的类名 var type = obj.GetType(); //typeof(Person) var className = type.Name; //类名:Person //propertyInfos获得类里面所有的属性 var propertyInfos = type.GetProperties(); var propNames = new string[propertyInfos.Length - 1]; //排除掉Id var paramNames = new string[propertyInfos.Length - 1]; var sqlParameters = new MySqlParameter[propertyInfos.Length - 1]; // Dictionary<string, object> dic = new Dictionary<string, object>(); var count = 0; foreach (var propInfo in propertyInfos) { var propName = propInfo.Name; if (propName != "Id") //排除Id { //遍历赋值,包含ID不进入赋值 propNames[count] = propName; paramNames[count] = "@" + propName; var mySqlParameter = new MySqlParameter(); mySqlParameter.ParameterName = "@" + propName; mySqlParameter.Value = propInfo.GetValue(obj); //去obj对象属性的值 sqlParameters[count] = mySqlParameter; count++; } } //拼接生成insert语句 var sbSql = new StringBuilder(); sbSql.Append("insert into ") .Append(className) .Append("(") .Append(string.Join(",", propNames)) .Append(")"); sbSql.Append(" values (").Append(string.Join(",", paramNames)).Append(")"); DbSqlhelper.ExecuteNonQuery(sbSql.ToString(), sqlParameters); //params可变长度参数本质上就是一个数组 } public static object SelectById(Type type, int id) { //将表名获取到 var classname = type.Name; var sql = "select * from " + classname + " where id=@id"; var dictionary = new Dictionary<string, object>(); dictionary["@id"] = id; var dataTable = DbSqlhelper.ExecuteQuery(sql, dictionary); if (dataTable.Rows.Count <= 0) { return null; } if (dataTable.Rows.Count > 1) { throw new Exception("查到多条ID=" + id + "的数据"); } var row = dataTable.Rows[0]; //创建type类的一个对象 var obj = Activator.CreateInstance(type); //给obj对象的每一个属性(包括Id)赋值,得到id name weight foreach (var propInfo in type.GetProperties()) { var propName = propInfo.Name; //属性名就是别名 var value = row[propName]; //获取数据库中列的值 propInfo.SetValue(obj, value); //给obj对象的propinfo属性赋值为value } return obj; } public static T SelectById<T>(int id) where T : new() //泛型约束,约束T必须有一个无参的构造函数 { var type = typeof (T); //typeof(Person) var classname = type.Name; var sql = "select * from " + classname + " where id=@id"; var dictionary = new Dictionary<string, object>(); dictionary["@id"] = id; var dataTable = DbSqlhelper.ExecuteQuery(sql, dictionary); if (dataTable.Rows.Count <= 0) { return default(T); //default(T)运算符用来获得类型的默认值 //default(int)→0 default(bool)→false default(Person)→null } if (dataTable.Rows.Count > 1) { throw new Exception("查到多条ID=" + id + "的数据"); } var row = dataTable.Rows[0]; //创建type类的一个对象 // var obj = Activator.CreateInstance(type); var obj = new T(); //泛型约束 //给obj对象的每一个属性(包括Id)赋值 返回当前 Type 的所有公共属性。 foreach (var propInfo in type.GetProperties()) { var propName = propInfo.Name; //属性名就是别名 var value = row[propName]; //获取数据库中列的值 propInfo.SetValue(obj, value); //给obj对象的propinfo属性赋值为value } return obj; } public static bool DeleteById(Type type, int id) { var classname = type.Name; var sql = "delete from " + classname + " where id=@id "; var i = DbSqlhelper.ExecuteNonQuery(sql, new MySqlParameter {ParameterName = "@id", Value = id}); //delete from dog where name='孔老二4' return i > 0; } public static bool UpdateById(object obj) { var type = obj.GetType(); var classname = type.Name; //获得表名 var propertyInfos = type.GetProperties(); //获得表名中的功能属性 var propNames = new string[propertyInfos.Length]; //获取该属性的长度 var paramNames = new string[propertyInfos.Length]; var sqlParameters = new MySqlParameter[propertyInfos.Length]; var count = 0; foreach (var propInfo in propertyInfos) { var propName = propInfo.Name; var mySqlParameter = new MySqlParameter(); mySqlParameter.ParameterName = "@" + propName; mySqlParameter.Value = propInfo.GetValue(obj); //去obj对象属性的值 sqlParameters[count] = mySqlParameter; if (propName != "Id") //排除Id { //遍历赋值,包含ID不进入赋值 propNames[count] = propName; //name paramNames[count] = propName + "=@" + propName; //@name } count++; } var oop = string.Join(" , ", paramNames).Substring(4); // sqlParameters; var sb = new StringBuilder(); sb.Append("update ").Append(classname).Append(" set ").Append(oop).Append(" where id=@id"); var sqltxt = sb.ToString(); var i = DbSqlhelper.ExecuteNonQuery(sqltxt, sqlParameters); //生成update语句 //update dog set name=@name weight=@weight where id=@id //怎么知道那一列被修改了呢 //把所有列都更新一下。反正不变的还是不变 return i > 0; } } }
主程序:
using System; namespace RupengORM { internal class Program { private static void Main(string[] args) { //ORM:EF(entity framework,Dapper,Nhibernate) // Person p1=new Person(); // p1.Name = "rupeng"; // p1.Age = 7; // RPorm.Insert(p1); for (var i = 0; i < 10; i++) { var d1 = new Dog(); d1.Name = "孔老二" + i; d1.Weight = 30; RPorm.Insert(d1); } //Person p1 = (Person)RPorm.SelectById(typeof(Person),1); //Console.WriteLine(p1.Name+"的年龄是"+p1.Age); // Dog p2 = (Dog)RPorm.SelectById(typeof(Dog), 1); //if (p2 == null) //{ // Console.WriteLine("没找到狗"); //} //else //{ // Console.WriteLine(p2.Name); //} //Dog dog = RPorm.SelectById<Dog>(1); //Console.WriteLine(dog.Name); // Type type = new Type typeof(Dog); //bool aa= RPorm.DeleteById(typeof(Dog),2); //Console.WriteLine(aa); var dog = new Dog(); dog.Weight++; dog.Name = "孔老二"; dog.Id = 9; var update = RPorm.UpdateById(dog); Console.WriteLine(update); Console.ReadKey(); } } }
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