Excel IF to SQL CASE WHEN

A spreadsheet IF is a CASE. Nested IFs are just more WHENs. Do not nest CASE inside CASE unless you must.

CASE
  WHEN total_amount > 10000 THEN 'Tier 1'
  WHEN total_amount > 1000 THEN 'Tier 2'
  ELSE 'Other'
END AS tier

SQL Server also has IIF(test, a, b). Fine for one test. Three bands belong in CASE.

Canonical translation

CASE
  WHEN total_amount > 10000 THEN 'Tier 1'
  WHEN total_amount > 1000 THEN 'Tier 2'
  ELSE 'Other'
END AS tier