Use ROW_NUMBER() to keep only the newest row in each group.
Join a table to itself to list each employee next to their manager, keeping the top-level employee who has no manager.
An anti-join with NOT EXISTS: find rows in one table that have no match in another, safely, even when the other table contains NULLs.
The classic interview question: find the 2nd (or Nth) highest salary, treating employees on the same salary as one rank.
Number the rows in each group of duplicates with ROW_NUMBER and delete all but the first. Preview first, then delete.
Add up values row by row in date order using SUM() OVER with an explicit ROWS frame, which is faster and handles ties correctly.
A half-open date range that works whether the column holds dates or date-times, and that can still use an index.
A SQL Server habit that prevents the classic disaster of updating every row: preview the rows, change them inside a transaction, check the count, then commit or roll back.
List values that appear more than once, with how often each occurs.
Two lines to center a child horizontally and vertically.
Cards that fill the row and wrap automatically, each at least 240px wide.