/// <summary>
/// 根据条件查找对象
/// </summary>
/// <param name="wh">where表达式</param>
/// <returns>返回实体或默认值</returns>
public T FirstOrDefault(Expression <Func <T, bool> > wh)
{
return(_ctx.Set <T>().FirstOrDefault(wh));
}
/// <summary>
/// 根据条件查找对象
/// </summary>
/// <param name="wh">where表达式</param>
/// <returns>返回实体或默认值</returns>
public T FirstOrDefault(Expression <Func <T, bool> > wh)
{
return(_ctx.Set <T>().FirstOrDefault(wh));
}