using t-sql date function to get records older than 10 days

i'm using sql server 2008

I have a table that looks like this:


This is the script to create this table.

USE [TestDatabase]
GO

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Orders1](
	[OrderID] [int] NULL,
	[CustomerID] [nvarchar](255) NULL,
	[EmployeeID] [int] NULL,
	[OrderDate] [datetime] NULL,
	[Freight] [decimal](20, 2) NULL
) ON [PRIMARY]

GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11074, N'SIMOB', 7, CAST(N'2018-04-24T09:34:00.000' AS DateTime), CAST(18.44 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11075, N'RICSU', 8, CAST(N'2018-04-23T08:30:00.000' AS DateTime), CAST(6.19 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11076, N'BONAP', 4, CAST(N'2018-04-23T07:10:00.000' AS DateTime), CAST(38.28 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11077, N'RATTC', 1, CAST(N'2018-04-20T08:20:00.000' AS DateTime), CAST(8.53 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11070, N'LEHMS', 2, CAST(N'2018-04-15T10:23:00.000' AS DateTime), CAST(136.00 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11071, N'LILAS', 1, CAST(N'2018-04-14T08:00:00.000' AS DateTime), CAST(0.93 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11072, N'ERNSH', 4, CAST(N'2018-04-14T06:34:00.000' AS DateTime), CAST(258.64 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11073, N'PERIC', 2, CAST(N'2018-04-12T01:00:00.000' AS DateTime), CAST(24.95 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11067, N'DRACD', 1, CAST(N'2018-04-11T09:00:00.000' AS DateTime), CAST(7.98 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11068, N'QUEEN', 8, CAST(N'2018-04-10T08:22:00.000' AS DateTime), CAST(81.75 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11069, N'TORTU', 1, CAST(N'2018-04-10T08:20:00.000' AS DateTime), CAST(15.67 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11064, N'SAVEA', 1, CAST(N'2018-04-09T09:40:00.000' AS DateTime), CAST(30.09 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11065, N'LILAS', 8, CAST(N'2018-04-08T00:00:00.000' AS DateTime), CAST(12.91 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11066, N'WHITC', 7, CAST(N'2018-04-07T09:20:00.000' AS DateTime), CAST(44.72 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11060, N'FRANS', 2, CAST(N'2018-04-06T00:00:00.000' AS DateTime), CAST(10.98 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11061, N'GREAL', 4, CAST(N'2018-04-05T05:34:00.000' AS DateTime), CAST(14.01 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11062, N'REGGC', 4, CAST(N'2018-04-04T05:10:00.000' AS DateTime), CAST(29.93 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11063, N'HUNGO', 3, CAST(N'2018-04-03T04:50:00.000' AS DateTime), CAST(81.73 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11057, N'NORTS', 3, CAST(N'2018-04-02T02:32:00.000' AS DateTime), CAST(4.13 AS Decimal(20, 2)))
GO
INSERT [dbo].[Orders1] ([OrderID], [CustomerID], [EmployeeID], [OrderDate], [Freight]) VALUES (11058, N'BLAUS', 9, CAST(N'2018-04-01T02:30:00.000' AS DateTime), CAST(31.14 AS Decimal(20, 2)))
GO

Select allOpen in new window

What's the most efficient query to return all orders whose OrderDate is older than 10 days from today's date?
So get today's date form using date function and return all orders older than 10 days.