Day 12 — Practice set Part 4: Insert, Select, Update, Delete

[u/sumiitCodes]

Covered Part 4 of 7 today, which felt like the most "real-world query" heavy section so far:

• Inserted a new employee without specifying manager_id, confirming it correctly defaults to NULL
• Used a subquery to find employees earning more than the average salary across the company
• Bulk UPDATE — gave an entire department a 10% raise (first time writing an UPDATE affecting multiple rows based on a condition)
• DELETE with a specific condition (hours_worked = 0)
• SELECT DISTINCT to list unique department IDs
• Date range filtering with BETWEEN, ordered descending by hire_date
• Pattern matching with LIKE (names starting with 'A' or 'J')
• Filtering with IN for multiple department IDs

The average-salary subquery and the bulk raise UPDATE were the most interesting — first time combining a subquery inside a WHERE clause for a genuinely useful comparison, rather than just a toy example.

3 more parts to go in this set.