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School Records SQL: Data Cleanup Queries

A 2-page snippet pack for data cleanup and maintenance queries for a school records database (students and enrollments): 12 short entries with copy-ready code.

ForDevelopers

sql-cleanup-queries-for-school-records.pdfShowing 18 of 72 lines
// Find duplicate student_number
SELECT student_number, count(*)
FROM students
GROUP BY student_number
HAVING count(*) > 1;

// Delete duplicates, keep the newest
DELETE FROM students
WHERE id IN (
  SELECT id FROM (
    SELECT id, row_number() OVER (PARTITION BY lower(student_number) ORDER BY id DESC) AS rn
    FROM students
  ) t
  WHERE rn > 1
);

// Trim stray whitespace
UPDATE students

What's inside

Format
PDF, Markdown, SQL
Contents
12 queries
Version
1.0 · Updated 3 Oct 2026
Licence
Commercial What this means
Checked
Checked before it ships
  • sql-cleanup-queries-for-school-records.pdfPDF · 21 KB
  • sql-cleanup-queries-for-school-records.mdMarkdown · 2 KB
  • sql-cleanup-queries-for-school-records.sqlSQL · 2 KB
  • LICENSE.txtadded to every download

About this item

A compact, printable snippet pack for data cleanup and maintenance queries for a school records database (students and enrollments). Each of the 12 entries has a one-line explanation and a small example you can paste into your editor. The PDF uses a two-column A4 layout designed to sit next to your keyboard, and the same content ships as Markdown so you can search it or drop it into your notes, plus a .sql file with every query. Every SQL example targets PostgreSQL 16.

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