Data Modification

1. 🚧 INSERT Patterns — Single row, multi-row, INSERT…SELECT, SELECT INTO.
2. 🚧 UPDATE with JOIN & OUTPUT — Join in UPDATE; capture changes with OUTPUT.
3. 🚧 DELETE Patterns — Delete with WHERE/JOIN; soft delete approaches.
4. 🚧 MERGE (safe upserts) — Upserts with MERGE and caveats.
5. 🚧 Identity & Sequences — IDENTITY columns and SQL Server SEQUENCE.