Coincidencia de SQL en la disposición de letras y números sin usar expresiones regulares

Prueba esto:

SELECT myCol 
FROM myTable 
WHERE SUBSTRING(myCol, 1 , 1) >= 'A' 
AND SUBSTRING(myCol, 1 , 1) <= 'Z' 
AND SUBSTRING(myCol, 2 , 1) >= 'A' 
AND SUBSTRING(myCol, 2 , 1) <= 'Z' 
AND SUBSTRING(myCol, 3 , 1) >= '0' 
AND SUBSTRING(myCol, 3 , 1) <= '9'