IS DISTINCT FROM compares nullable values without inventing a sentinel. Test two NULLs, one NULL and changed values, then use the predicate to find transitions that ordinary equality can miss.
GTIN-13 Check Digits: Validate the Final Digit in a CHECK Constraint
A GTIN-13 check digit validates a weighted checksum, not product identity. Test complete ASCII input, leading zeros and the final digit in a CHECK constraint, then see why some digit swaps still pass.
SQL Server Execution Plan Quiz: One Table, Two Operators
One table reference can produce Nested Loops, a Key Lookup and parallel operators in an execution plan. A controlled SQL example makes the work visible and shows why MAXDOP is a ceiling rather than a promise of parallel execution.
Late-Arriving Dimension Rows: Inferred Members in a Data Warehouse
Handle a late-arriving dimension with inferred members, preserve fact keys, fill attributes later, and report unresolved placeholders.
LocalDB: SQL Server on a Developer’s Laptop
LocalDB runs SQL Server Express engine features in a developer-friendly local process; learn how to start, connect, and recognize its limits.
geometry STNumPoints: Closing Coordinates Count Again
geometry STNumPoints counts coordinates in the spatial description. A square ring contains its closing coordinate as well as its four distinct corners.
geometry STGeometryType: Type Names Say More Than Dimension
geometry STGeometryType identifies the represented shape type, which carries more information than its dimension. I compare single and multiple shapes in one small query. Equal dimensions do not mean that their structures are interchangeable.