IF EXISTS (SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'usuario' AND COLUMN_NAME = 'identif')
BEGIN
	IF ((SELECT CHARACTER_MAXIMUM_LENGTH FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'usuario' AND COLUMN_NAME = 'identif') < 255)
	BEGIN
		ALTER TABLE usuario ALTER COLUMN identif VARCHAR(255)
	END
END