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自己动手写ORM框架(九):实现删除功能Remove方法

前面简单的修改功能已经实现了，下面是实现删除功能，代码1-1如下：

#region 删除实体对应数据库中的数据
public int Remove<T>(T entity)
{
    TableInfo tableInfo = DbEntityUtils.GetTableInfo(entity, DbOperateType.DELETE);

    string strSql = DbEntityUtils.GetDeleteByIdSql(tableInfo);

    IDbDataParameter[] parms = DbFactory.CreateDbParameters(1);

    parms[0].ParameterName = tableInfo.Id.Key;

    parms[0].Value = tableInfo.Id.Value;

    object val = AdoHelper.ExecuteNonQuery(transaction, CommandType.Text, strSql, parms);

    return Convert.ToInt32(val);
}
#endregion

#region 根据主键id删除实体对应数据库中的数据
public int Remove<T>(object id) where T : new()
{
    TableInfo tableInfo = DbEntityUtils.GetTableInfo(new T(), DbOperateType.DELETE);

    string strSql = DbEntityUtils.GetDeleteByIdSql(tableInfo);

    IDbDataParameter[] parms = DbFactory.CreateDbParameters(1);

    parms[0].ParameterName = tableInfo.Id.Key;

    parms[0].Value = id;

    object val = AdoHelper.ExecuteNonQuery(transaction, CommandType.Text, strSql, parms);

    return Convert.ToInt32(val);
}
#endregion

DbEntityUtils.GetDeleteByIdSql方法代码如下1-2:

public static string GetDeleteByIdSql(TableInfo tableInfo)
{
    string strSql = "delete {0} where {1} =" + AdoHelper.DbParmChar + tableInfo.Id.Key;
    strSql = string.Format(strSql, tableInfo.TableName, tableInfo.Id.Key);
    return strSql;
}

到这里为止简单的增、删、改、查功能都已完成，还有许多复杂的操作需要完成，但需要大量的时间和精力，这里只是分享一种思路或是作技术交流，所以不再继续深入的研究下去了，如有兴趣的也可以继续研究和分享经验。

下面是几个类的代码，EntityManagerImpl类：

EntityManagerImplusing System;
using System.Collections.Generic;
using System.Text;
using System.Reflection;
using System.Orm.CustomAttributes;
using System.Data.SqlClient;
using System.Collections;
using System.Data;
using System.Orm.DBUtility;
using System.Orm.Common;

namespace System.Orm.EntityManager
{
    public class EntityManagerImpl : EntityManager
    {
        IDbTransaction transaction = null;

        #region 将实体数据保存到数据库
        public int Save<T>(T entity)
        {
            TableInfo tableInfo = DbEntityUtils.GetTableInfo(entity, DbOperateType.INSERT);

            String strSql = DbEntityUtils.GetInsertSql(tableInfo);

            IDbDataParameter[] parms = DbFactory.CreateDbParameters(tableInfo.Columns.Count);

            DbEntityUtils.SetParameters(tableInfo.Columns, parms);

            object val = AdoHelper.ExecuteNonQuery(transaction, CommandType.Text, strSql, parms);

            return Convert.ToInt32(val);
        }
        #endregion

        #region 将实体数据修改到数据库
        public int Update<T>(T entity)
        {
            TableInfo tableInfo = DbEntityUtils.GetTableInfo(entity, DbOperateType.UPDATE);

            String strSql = DbEntityUtils.GetUpdateSql(tableInfo);

            IDbDataParameter[] parms = DbFactory.CreateDbParameters(tableInfo.Columns.Count);

            DbEntityUtils.SetParameters(tableInfo.Columns, parms);

            object val = AdoHelper.ExecuteNonQuery(transaction, CommandType.Text, strSql, parms);

            return Convert.ToInt32(val);
        }
        #endregion

        #region 删除实体对应数据库中的数据
        public int Remove<T>(T entity)
        {
            TableInfo tableInfo = DbEntityUtils.GetTableInfo(entity, DbOperateType.DELETE);

            String strSql = DbEntityUtils.GetDeleteByIdSql(tableInfo);

            IDbDataParameter[] parms = DbFactory.CreateDbParameters(1);
            parms[0].ParameterName = tableInfo.Id.Key;
            parms[0].Value = tableInfo.Id.Value;

            object val = AdoHelper.ExecuteNonQuery(transaction, CommandType.Text, strSql, parms);

            return Convert.ToInt32(val);
        }
        #endregion

        #region 根据主键id删除实体对应数据库中的数据
        public int Remove<T>(object id) where T : new()
        {
            TableInfo tableInfo = DbEntityUtils.GetTableInfo(new T(), DbOperateType.DELETE);

            String strSql = DbEntityUtils.GetDeleteByIdSql(tableInfo);

            IDbDataParameter[] parms = DbFactory.CreateDbParameters(1);
            parms[0].ParameterName = tableInfo.Id.Key;
            parms[0].Value = id;

            object val = AdoHelper.ExecuteNonQuery(transaction, CommandType.Text, strSql, parms);

            return Convert.ToInt32(val);
        }
        #endregion

        #region 查询实体对应表的所有数据
        public List<T> FindAll<T>() where T : new()
        {
            List<T> listArr = new List<T>();
            PropertyInfo[] properties = ReflectionUtils.GetProperties(new T().GetType());

            TableInfo tableInfo = DbEntityUtils.GetTableInfo(new T(), DbOperateType.SELECT);

            String strSql = DbEntityUtils.GetFindAllSql(tableInfo);

            IDataReader sdr = null;
            try
            {
                sdr = AdoHelper.ExecuteReader(AdoHelper.ConnectionString, CommandType.Text, strSql);
                while (sdr.Read())
                {
                    T entity = new T();
                    foreach (PropertyInfo property in properties)
                    {
                        String name = tableInfo.PropToColumn[property.Name].ToString();
                        ReflectionUtils.SetPropertyValue(entity, property, sdr[name]);
                    }

                    listArr.Add(entity);
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                if (sdr != null) sdr.Close();
            }

            return listArr;
        }
        #endregion

        #region 通过自定义SQL语句查询数据
        public List<T> FindBySql<T>(string strSql) where T : new()
        {
            List<T> listArr = new List<T>();
            Type classType = new T().GetType();
            PropertyInfo[] properties = ReflectionUtils.GetProperties(classType);

            IDataReader sdr = null;
            try
            {
                sdr = AdoHelper.ExecuteReader(AdoHelper.ConnectionString, CommandType.Text, strSql);
                while (sdr.Read())
                {
                    T entity = new T();
                    foreach (PropertyInfo property in properties)
                    {
                        ReflectionUtils.SetPropertyValue(entity, property, sdr[property.Name]);
                    }

                    listArr.Add(entity);
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                if (sdr != null) sdr.Close();
            }

            return listArr;
        }
        #endregion

        #region 通过主键ID查询数据
        public List<T> FindById<T>(object id) where T : new()
        {
            List<T> listArr = new List<T>();
            PropertyInfo[] properties = ReflectionUtils.GetProperties(new T().GetType());

            TableInfo tableInfo = DbEntityUtils.GetTableInfo(new T(), DbOperateType.SELECT);

            String strSql = DbEntityUtils.GetFindByIdSql(tableInfo);

            IDbDataParameter[] parms = DbFactory.CreateDbParameters(1);
            parms[0].ParameterName = tableInfo.Id.Key;
            parms[0].Value = id;

            IDataReader sdr = null;
            try
            {
                sdr = AdoHelper.ExecuteReader(AdoHelper.ConnectionString, CommandType.Text, strSql, parms);
                while (sdr.Read())
                {
                    T entity = new T();
                    foreach (PropertyInfo property in properties)
                    {
                        String name = tableInfo.PropToColumn[property.Name].ToString();
                        ReflectionUtils.SetPropertyValue(entity, property, sdr[name]);
                    }

                    listArr.Add(entity);
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                if (sdr != null) sdr.Close();
            }

            return listArr;
        }
        #endregion

        #region Transaction 注入事物对象属性
        public IDbTransaction Transaction
        {
            get
            {
                return transaction;
            }
            set
            {
                transaction = value;
            }
        }
        #endregion
    }
}

EntityManagerFactory类：

EntityManagerFactoryusing System;
using System.Collections.Generic;
using System.Text;
using System.Configuration;

namespace System.Orm.EntityManager
{
    public class EntityManagerFactory
    {
        public static EntityManager CreateEntityManager()
        {
            return new EntityManagerImpl();
        }
    }
}

TransactionManager类：

TransactionManagerusing System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Configuration;
using System.Data.SqlClient;
using System.Data.OracleClient;
using System.Data.Common;
using System.Orm.DBUtility;

namespace System.Orm.DBTransaction
{
    public class TransactionManager
    {   
        public static IDbTransaction CreateTransaction()
        {
            return DbFactory.CreateDbTransaction();
        }
    }
}

StudentDAL调用类：

StudentDALusing System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using Entity;
using System.Orm.EntityManager;
using System.Orm.DBTransaction;

namespace DAL
{
    public class StudentDAL
    {
        EntityManager entityManager = EntityManagerFactory.CreateEntityManager();

        public StudentDAL() { }
        public StudentDAL(IDbTransaction transaction)
        {
            entityManager.Transaction = transaction;
        }

        public List<StudentEntity> FindAll()
        {
            return entityManager.FindAll<StudentEntity>();
        }
        
        public int Save(StudentEntity entity)
        {
            return entityManager.Save(entity);
        }

        public int Update(StudentEntity entity)
        {
            return entityManager.Update(entity);
        }

        public int Remove(StudentEntity entity)
        {
            return entityManager.Remove(entity);
        }

        public int Remove(object id)
        {
            return entityManager.Remove<StudentEntity>(id);
        }               

        public List<StudentEntity> FindById(object id)
        {
            return entityManager.FindById<StudentEntity>(id);
        }        
    }
}

有一些园友希望能提供源码，这里将提供源码下载地址：OrmTest.rar下载

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原文地址：https://www.cnblogs.com/wangwei123/p/1770598.html