What databases have you worked with? Through ORM or native queries? What native queries did you write and at what level?

Worked with various databases: PostgreSQL, MySQL, MongoDB, Redis. Mainly used ORM (e.g., GORM for Go) to speed up development and convenience, but for complex queries and optimization, wrote native SQL queries.

Examples of native queries:

• Complex JOINs with aggregations and subqueries
• Use of window functions
• Optimized queries using indexes and filters

Level — confident in SQL, including writing complex queries, optimization, and understanding execution plans. In Go, used the database/sql package and sqlx for ease of working with native queries.

Example of a native query in Go using database/sql:

query := `SELECT id, name FROM users WHERE age > $1 ORDER BY created_at DESC LIMIT 10`
rows, err := db.Query(query, 30)
if err != nil {
    log.Fatal(err)
}
// process rows

Using ORM allows for quick start, but for performance-critical sections, I always prefer native queries.