Вот таблица с тестовыми данными
CREATE TABLE [dbo].[TableTest](
[Id] [int] IDENTITY(1,1) NOT NULL,
[stringwithnumeric] [varchar](50) NULL,
CONSTRAINT [PK_TableTest] PRIMARY KEY CLUSTERED
(
[Id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
SET IDENTITY_INSERT [dbo].[TableTest] ON
INSERT [dbo].[TableTest] ([Id], [stringwithnumeric]) VALUES (1, N'1')
INSERT [dbo].[TableTest] ([Id], [stringwithnumeric]) VALUES (2, N'dsa')
INSERT [dbo].[TableTest] ([Id], [stringwithnumeric]) VALUES (3, N'3')
INSERT [dbo].[TableTest] ([Id], [stringwithnumeric]) VALUES (4, N'3')
INSERT [dbo].[TableTest] ([Id], [stringwithnumeric]) VALUES (5, N'gg')
INSERT [dbo].[TableTest] ([Id], [stringwithnumeric]) VALUES (6, N'del')
INSERT [dbo].[TableTest] ([Id], [stringwithnumeric]) VALUES (7, N'33')
INSERT [dbo].[TableTest] ([Id], [stringwithnumeric]) VALUES (8, N'67')
INSERT [dbo].[TableTest] ([Id], [stringwithnumeric]) VALUES (9, N'97')
SET IDENTITY_INSERT [dbo].[TableTest] OFF
Вот запрос
SELECT
Id
,stringwithnumeric
FROM dbo.TableTest
WHERE ISNUMERIC (stringwithnumeric)=1
Или что-то другое хотелось?