WITH FECODE AS(
SELECT SUM(CODE) AS FECODE FROM SKILLCODES WHERE CATEGORY = 'Front End'
), PYCODE AS(
SELECT CODE AS PYCODE FROM SKILLCODES WHERE NAME = 'Python'
), CSCODE AS(
SELECT CODE AS CSCODE FROM SKILLCODES WHERE NAME = 'C#'
), GRDEVS AS(
SELECT
CASE
WHEN (SKILLCODE & FECODE) AND (SKILLCODE & PYCODE) THEN 'A'
WHEN SKILLCODE & CSCODE THEN 'B'
WHEN SKILLCODE & FECODE THEN 'C'
END AS GRADE
, ID, EMAIL
FROM DEVELOPERS, FECODE, PYCODE, CSCODE
)
SELECT * FROM GR_DEVS WHERE GRADE IS NOT NULL ORDER BY GRADE ASC, ID ASC