/// <summary>
/// 字段累加（字段 = 字段 + 值）
/// </summary>
/// <typeparam name="T">值类型</typeparam>
/// <param name="fieldName">字段选择器</param>
/// <param name="fieldValue">值</param>
public virtual TSet Append <T>(Expression <Func <TEntity, object> > fieldName, T fieldValue) where T : struct
{
Queue.AddAssign(fieldName, fieldValue);
return((TSet)this);
}