Big Data Analytics answers four kinds of questions: what happened, why it happened, what will happen next and what to do about it. This post climbs that ladder with one small business and shows each step in T-SQL window functions.
The PRODUCT Aggregate: Multiplying Values Across Rows
Use the PRODUCT aggregate in SQL Server 2025 for growth factors and independent probabilities, with checks for NULL, zero, and precision.
Integer Division in T-SQL: Why Your Percentages Come Out Zero
Fix integer division in T-SQL percentages from COUNT, SUM and window calculations with decimal types and rounding at the right step.
Generating Random Numbers Per Row: RAND, NEWID and CRYPT_GEN_RANDOM
Generate random numbers per row with NEWID or CRYPT_GEN_RANDOM, compare seeded RAND, inspect bucket spread, and pick a row without a sort.
Whole Unit Allocation: Keep a Proportional Split Exact
Whole unit allocation keeps a fixed budget intact. I’d calculate base shares first, then distribute residual units using a stable tie rule. Check equal weights, a zero budget and zero-weight members.
VAR and VARP: Choose the Variance Denominator
VAR and VARP describe sample and population variation. Keep observation count and missingness visible when reporting their results.
SIGN: Classify Positive, Negative and Zero Values
SIGN describes which side of zero an amount occupies. Preserve the original quantity and distinguish a zero value from missing input.