How to combine multiple selects in one query - Databases - ( loop reference )

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Fri Aug 13 2021 20:37:28 GMT+0000 (Coordinated Universal Time)

Saved by @mvieira

SELECT
    1 AS Deptnumber
  , Dept
FROM tbl_students
WHERE Dept IN ('A', 'B', 'C')
UNION
SELECT
    2 AS DeptNumber
  , Dept
FROM tbl_students
WHERE Dept IN ('D', 'E')
UNION
SELECT
    3 AS Deptnumber
  , Dept
FROM tbl_students
WHERE Dept IN ('F')


Reference : 
https://stackoverflow.com/questions/1775168/multiple-select-statements-in-single-query
https://kb.objectrocket.com/postgresql/postgres-loop-types-1027
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https://www.sitepoint.com/community/t/how-to-combine-multiple-selects-in-one-query/7741