Delete Duplicate Records

Delete Duplicate Records is a MySQL topic you learn with one small college example — a students table with roll, name, marks. Say what Delete Duplicate Records does in one sentence, then write the shortest SQL that shows it.

Pattern: USE college; then a CREATE/SELECT/UPDATE that needs Delete Duplicate Records. If it is a function, SELECT it on one column. If it is DDL, run SHOW / DESCRIBE after so you can see the change.

Trap: only reciting the heading Delete Duplicate Records with no SQL. Interviewers ask you to type. Another trap: mixing this up with a neighbouring command (DELETE vs TRUNCATE vs DROP, WHERE vs HAVING, JOIN vs UNION).

Keep the example on paper — two or three rows. Change one value. Predict the result before you run it.

On the example next to this theory: Delete Duplicate Records — dELETE removes matching rows. TRUNCATE clears a whole table faster (MySQL).

Exam tip

What is Delete Duplicate Records? One sentence + one tiny SQL on students.

Delete Duplicate Records — sample query

CREATE TABLE tags (id INTEGER PRIMARY KEY, label TEXT);
INSERT INTO tags VALUES (1, 'old'), (2, 'keep');
DELETE FROM tags WHERE label = 'old';
SELECT * FROM tags;

Delete Duplicate Records — dELETE removes matching rows. TRUNCATE clears a whole table faster (MySQL).

Short notes

DefDelete Duplicate Records — explain with students(roll, name, marks).
RuleShortest SQL that uses Delete Duplicate Records. Then SHOW/SELECT the effect.
TrapHeading only, no query. Mixing nearby commands.

Delete Duplicate Records

Pattern: USE college; then a CREATE/SELECT/UPDATE that needs Delete Duplicate Records. If it is a function, SELECT it on one column. If it is DDL, run SHOW / DESCRIBE after so you can see the change.

Keep the example on paper — two or three rows. Change one value. Predict the result before you run it.

On the example next to this theory: Delete Duplicate Records — dELETE removes matching rows. TRUNCATE clears a whole table faster (MySQL).

Exam tip

What is Delete Duplicate Records? One sentence + one tiny SQL on students.

Delete Duplicate Records — sample query

CREATE TABLE tags (id INTEGER PRIMARY KEY, label TEXT);
INSERT INTO tags VALUES (1, 'old'), (2, 'keep');
DELETE FROM tags WHERE label = 'old';
SELECT * FROM tags;

Delete Duplicate Records — dELETE removes matching rows. TRUNCATE clears a whole table faster (MySQL).

Short notes

DefDelete Duplicate Records — explain with students(roll, name, marks).
RuleShortest SQL that uses Delete Duplicate Records. Then SHOW/SELECT the effect.
TrapHeading only, no query. Mixing nearby commands.

Delete Duplicate Records

Delete Duplicate Records — sample query

Short notes

Questions

Delete Duplicate Records

Delete Duplicate Records — sample query

Short notes

Questions