Verificare se un campo di una tabella è un numero

USE tempdb;

CREATE TABLE dbo.t(
c char(4) NOT NULL
)

INSERT dbo.t VALUES('0a3d');
INSERT dbo.t VALUES('0015');
INSERT dbo.t VALUES('af1d');
INSERT dbo.t VALUES('1234');

SELECT
      c
    , CASE ISNUMERIC(c)
          WHEN 1 THEN 'Numero'
          ELSE 'Testo'
      END AS Tipo
FROM dbo.t;

/* Output:

c    Tipo
---- ------
0a3d Testo
0015 Numero
af1d Testo
1234 Numero

(4 row(s) affected)

*/

WITH CTE_Tipo AS
(
    SELECT
        CASE ISNUMERIC(c)
            WHEN 1 THEN 'Numero'
            ELSE 'Testo'
        END AS Tipo
    FROM dbo.t
)
SELECT Tipo, COUNT(*) AS Numero
FROM CTE_Tipo
GROUP BY Tipo;

/* Output:

Tipo   Numero
------ -----------
Numero 2
Testo  2

(2 row(s) affected)

*/

DROP TABLE dbo.t;

WITH CTE_Tipo AS
(
    SELECT
        CASE ISNUMERIC(c)
            WHEN 1 THEN 'Numero'
            ELSE 'Testo'
        END AS Tipo
    FROM dbo.t
)
SELECT Tipo, COUNT(*) AS Numero
FROM CTE_Tipo
GROUP BY Tipo;