EF架构~一个规范，两个实现（续）~性能可以接受的批量增删改操作

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上回主要把数据操作规范及EF两种基类下的实现说了一下，今天主要针对ObjectContext情况下的批量操作作一个详细的说明，首先，要说明一点，批量操作不用ObjectContext提供的方法，而是使用拼SQL串的方式，将列表拼成一个SQL串，一次的发给数据库，这样在性能上绝对是一个质的飞越，本人尝试过，无论是EF还是linq to sql，它们提供的方法，对于列表的操作会产生N条SQL串（N＝列表的长度）。

一个操作类型枚举：

        /// <summary>
        /// 執行SQL的類型
        /// </summary>
        public enum SQLType
        {
            Insert,
            Update,
            Delete,
        }

调用方法很容易：

public void Insert<TEntity>(List<TEntity> list) where TEntity : class
        {
            DoListSQL(list, SQLType.Insert);
        }

public void Update<TEntity>(List<TEntity> list) where TEntity : class
        {
            DoListSQL<TEntity>(list, SQLType.Update);
        }

  public void Delete<TEntity>(List<TEntity> list) where TEntity : class
        {
            DoListSQL<TEntity>(list, SQLType.Delete);
        }

下面是实现这样方法的代码，即SQL串在ObjectContext环境下是如何拼接的：

 /// <summary>
        /// 构建Update语句串
        /// </summary>
        /// <typeparam name="TEntity"></typeparam>
        /// <param name="entity"></param>
        /// <returns></returns>
        private Tuple<string, object[]> CreateUpdateSQL<TEntity>(TEntity entity) where TEntity : class
        {
            if (entity == null)
                throw new ArgumentException("The database entity can not be null.");

            Type entityType = entity.GetType();
            var table = entityType.GetProperties().Where(i => i.PropertyType != typeof(EntityKey) && i.PropertyType != typeof(EntityState)).ToArray();
            var primaryKeyColumns = (entity as EntityObject).GetPK();
            if (primaryKeyColumns == null || primaryKeyColumns.Count == 0)
                throw new ArgumentException("The Table entity have not a primary key.");
            List<object> arguments = new List<object>();
            StringBuilder builder = new StringBuilder();

            foreach (var change in table)
            {
                if (primaryKeyColumns.Contains(change))
                    continue;

                if (arguments.Count != 0)
                    builder.Append(", ");

                if (change.GetValue(entity, null) != null)
                {
                    builder.Append(change.Name + " = {" + arguments.Count + "}");

                    if (change.PropertyType == typeof(string) || change.PropertyType == typeof(DateTime))
                        arguments.Add("'" + change.GetValue(entity, null).ToString().Replace("'", "char(39)") + "'");
                    else
                        arguments.Add(change.GetValue(entity, null));
                }
                else
                {
                    builder.Append(change.Name + " = NULL, ");
                }
            }

            if (builder.Length == 0)
                throw new Exception("没有任何属性进行更新");

            builder.Insert(0, " UPDATE " + string.Format("[{0}]", entityType.Name) + " SET ");

            builder.Append(" WHERE ");
            bool firstPrimaryKey = true;

            foreach (var primaryField in primaryKeyColumns)
            {
                if (firstPrimaryKey)
                    firstPrimaryKey = false;
                else
                    builder.Append(" AND ");

                object val = entityType.GetProperty(primaryField.Name).GetValue(entity, null);
                builder.Append(GetEqualStatment(primaryField.Name, arguments.Count));
                arguments.Add(val);
            }
            return new Tuple<string, object[]>(builder.ToString(), arguments.ToArray());

        }

        /// <summary>
        /// 构建Insert语句串
        /// 主键为自增时，如果主键值为0，我们将主键插入到SQL串中
        /// </summary>
        /// <typeparam name="TEntity"></typeparam>
        /// <param name="entity"></param>
        /// <returns></returns>
        private Tuple<string, object[]> CreateInsertSQL<TEntity>(TEntity entity) where TEntity : class
        {
            if (entity == null)
                throw new ArgumentException("The database entity can not be null.");

            Type entityType = entity.GetType();
            var table = entityType.GetProperties().Where(i => i.PropertyType != typeof(EntityKey) && i.PropertyType != typeof(EntityState)).ToArray();
            var primaryKeyColumns = (entity as EntityObject).GetPK();

            List<object> arguments = new List<object>();
            StringBuilder fieldbuilder = new StringBuilder();
            StringBuilder valuebuilder = new StringBuilder();

            fieldbuilder.Append(" INSERT INTO " + string.Format("[{0}]", entityType.Name) + " (");

            foreach (var member in table)
            {
                if (primaryKeyColumns.Contains(member) && Convert.ToString(member.GetValue(entity, null)) == "0")
                    continue;
                object value = member.GetValue(entity, null);
                if (value != null)
                {
                    if (arguments.Count != 0)
                    {
                        fieldbuilder.Append(", ");
                        valuebuilder.Append(", ");
                    }

                    fieldbuilder.Append(member.Name);
                    if (member.PropertyType == typeof(string) || member.PropertyType == typeof(DateTime))
                        valuebuilder.Append("'{" + arguments.Count + "}'");
                    else
                        valuebuilder.Append("{" + arguments.Count + "}");
                    if (value.GetType() == typeof(string))
                        value = value.ToString().Replace("'", "char(39)");
                    arguments.Add(value);

                }
            }


            fieldbuilder.Append(") Values (");

            fieldbuilder.Append(valuebuilder.ToString());
            fieldbuilder.Append(");");
            return new Tuple<string, object[]>(fieldbuilder.ToString(), arguments.ToArray());
        }
        /// <summary>
        /// 构建Delete语句串
        /// </summary>
        /// <typeparam name="TEntity"></typeparam>
        /// <param name="entity"></param>
        /// <returns></returns>
        private Tuple<string, object[]> CreateDeleteSQL<TEntity>(TEntity entity) where TEntity : class
        {
            if (entity == null)
                throw new ArgumentException("The database entity can not be null.");

            Type entityType = entity.GetType();
            var table = entityType.GetProperties().Where(i => i.PropertyType != typeof(EntityKey) && i.PropertyType != typeof(EntityState)).ToArray();
            var primaryKeyColumns = (entity as EntityObject).GetPK();
            if (primaryKeyColumns == null || primaryKeyColumns.Count == 0)
                throw new ArgumentException("The Table entity have not a primary key.");

            List<object> arguments = new List<object>();
            StringBuilder builder = new StringBuilder();
            builder.Append(" Delete from " + string.Format("[{0}]", entityType.Name));

            builder.Append(" WHERE ");
            bool firstPrimaryKey = true;

            foreach (var primaryField in primaryKeyColumns)
            {
                if (firstPrimaryKey)
                    firstPrimaryKey = false;
                else
                    builder.Append(" AND ");

                object val = entityType.GetProperty(primaryField.Name).GetValue(entity, null);
                builder.Append(GetEqualStatment(primaryField.Name, arguments.Count));
                arguments.Add(val);
            }
            return new Tuple<string, object[]>(builder.ToString(), arguments.ToArray());
        }


        /// <summary>
        /// 执行实体列表以SQL串的方式
        /// </summary>
        /// <typeparam name="TEntity"></typeparam>
        /// <param name="list"></param>
        private void DoListSQL<TEntity>(IEnumerable<TEntity> list, SQLType sqlType) where TEntity : class
        {
            StringBuilder sqlstr = new StringBuilder();

            switch (sqlType)
            {
                case SQLType.Insert:
                    list.ToList().ForEach(i =>
                   {
                       Tuple<string, object[]> sql = CreateInsertSQL(i);
                       sqlstr.AppendFormat(sql.Item1, sql.Item2);
                   });
                    break;
                case SQLType.Update:
                    list.ToList().ForEach(i =>
                    {
                        Tuple<string, object[]> sql = CreateUpdateSQL(i);
                        sqlstr.AppendFormat(sql.Item1, sql.Item2);
                    });
                    break;
                case SQLType.Delete:
                    list.ToList().ForEach(i =>
                   {
                       Tuple<string, object[]> sql = CreateDeleteSQL(i);
                       sqlstr.AppendFormat(sql.Item1, sql.Item2);
                   });
                    break;
                default:
                    throw new ArgumentException("请输入正确的参数");
            }

            _db.ExecuteStoreCommand(sqlstr.ToString());
        }

代码在vs2010+sql2005+mvc3环境下测试通过

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