Ricardo, com o Where são permitidos apenas os seguintes comandos:
WHERE CustomerName LIKE 'a%'Finds any values that starts with "a"
WHERE CustomerName LIKE '%a'Finds any values that ends with "a"
WHERE CustomerName LIKE '%or%'Finds any values that have "or" in any position
WHERE CustomerName LIKE '_r%'Finds any values that have "r" in the second position
WHERE CustomerName LIKE 'a_%_%'Finds any values that starts with "a" and are at least 3 characters in length
WHERE ContactName LIKE 'a%o'Finds any values that starts with "a" and ends with "o"
Aquele * ali, é para quando você deseja retornar todas as linhas sem definição particular