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sql

Structured Query Language

DatabasesFind SQL Duplicates by Email & Name: GROUP BY Guide

Learn to find and remove SQL duplicates by multiple fields like email and name using GROUP BY, HAVING, window functions. Examples for detecting, retrieving full rows, and safe deletion in MySQL, PostgreSQL, SQL Server.

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ProgrammingSecure Parameter Passing in Gorm ORDER BY Clause

Learn how to securely pass parameters into Golang Gorm ORDER BY clauses using clause.Expr for custom ordering with array_position.

1 answer• 1 view
DatabasesUnderstanding MySQL Index Types: PRIMARY, UNIQUE, FULLTEXT

Learn the key differences between PRIMARY, UNIQUE, INDEX, and FULLTEXT index types in MySQL. Discover when to use each type for optimal database performance and design.

1 answer• 1 view
DatabasesOracle SQL: Get Max Date Row Per UserId (Latest Record)

Learn Oracle SQL techniques to fetch rows with maximum Date per UserId. Use ROW_NUMBER window function, JOIN subquery, NOT EXISTS, or KEEP DENSE_RANK for latest records efficiently on large tables.

1 answer• 1 view
DatabasesSQL Subquery Derived Table: Select All Sale Columns

Learn to use an SQL subquery as a derived table to select all columns from the Sale table for female customers (Gender='F'). Fix your query with INNER JOIN and DISTINCT for perfect results.

1 answer• 1 view