DISTINCT, Alias and ORDER BY

DISTINCT — Unique Rows

SELECT DISTINCT class FROM students;

Removes duplicate values from the result.

Alias — Rename in Output

SELECT name AS student_name, marks AS score
FROM students;

AS gives a column a friendlier name in the result (does not change the table).

ORDER BY — Sorting

SELECT name, marks FROM students ORDER BY marks DESC;
SELECT name FROM students ORDER BY name ASC;

Summary

• DISTINCT removes duplicates; AS renames output columns.
• ORDER BY sorts: ASC (default) or DESC.

DISTINCT — Unique Rows

SELECT DISTINCT class FROM students;

Result से duplicate values हटाता है।

Alias — Output में Rename

SELECT name AS student_name, marks AS score
FROM students;

AS result में column को आसान नाम देता है (table नहीं बदलता)।

ORDER BY — Sorting

SELECT name, marks FROM students ORDER BY marks DESC;
SELECT name FROM students ORDER BY name ASC;

सारांश

• DISTINCT duplicates हटाता है; AS output columns rename करता है।
• ORDER BY sort करता है: ASC (default) या DESC।