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Selected Java Interview Questions
Selected Java Interview Questions
Oct 17, 2023 · Databases

SQL Techniques: Finding Duplicate Records, TRUNCATE vs DELETE, Primary vs Candidate Keys, Second Highest Salary, and Common Interview Queries

This article explains how to locate duplicate rows in a table, contrasts TRUNCATE and DELETE commands, clarifies the difference between primary and candidate keys, demonstrates queries for retrieving the second highest salary, and provides a collection of typical SQL interview questions with sample code.

TRUNCATEduplicate recordsinterview-questions
0 likes · 9 min read
SQL Techniques: Finding Duplicate Records, TRUNCATE vs DELETE, Primary vs Candidate Keys, Second Highest Salary, and Common Interview Queries
Programmer DD
Programmer DD
Oct 27, 2020 · Databases

How to Find and Delete Duplicate Records in MySQL Efficiently

This article explains how to identify duplicate rows in a MySQL table using GROUP BY and HAVING, shows several SELECT queries to list duplicates, and provides multiple DELETE strategies—including sub‑queries and multi‑column handling—to safely remove excess records while keeping one copy.

DELETEGROUP BYduplicate records
0 likes · 9 min read
How to Find and Delete Duplicate Records in MySQL Efficiently
ITPUB
ITPUB
Dec 5, 2017 · Databases

How to Remove Duplicate MySQL Records with a Single Fast SQL Query

This article walks through the problem of duplicate rows in a MySQL table, shows an initial complex SQL attempt, compares a slow PHP‑based cleanup, and finally presents a concise, three‑step DELETE statement that eliminates duplicates in under a second.

data cleanupduplicate recordsmysql
0 likes · 6 min read
How to Remove Duplicate MySQL Records with a Single Fast SQL Query