CSV
Reconciling a Bank Statement CSV With Your Ledger in SQL
Match a bank statement CSV against a ledger in SQL with a date tolerance, pair duplicate amounts correctly, and explain the difference in totals row by row.
7 min read
Library
Everything you need to level up your coding skills.
CSV
Making Quick Charts From a CSV With Python and DuckDB
Make quick charts from a large CSV: aggregate in DuckDB, plot with matplotlib or draw text bars in the terminal, and keep the charts honest.
6 min read
CSV
Checking if a CSV Column Is Normally Distributed With Python
Test whether a CSV column follows a normal distribution using skew, kurtosis, percentiles and Shapiro-Wilk, and why a huge file always fails the test.
7 min read
CSV
Sampling a CSV for a Fast First Look at Large Data
Sample a large CSV for a quick first look: why the top rows mislead, random and reproducible sampling in DuckDB, and how the error shrinks with sample size.
6 min read
CSV
Finding the Top Customers by Revenue in a CSV File
Rank customers by revenue in a CSV with SQL, compute cumulative share and the top 10 percent, handle ties and refunds, and read the concentration curve.
7 min read
CSV
Comparing Two Time Periods in a CSV Without Being Fooled
Compare this month with last month from a CSV in SQL without being fooled by day counts, open periods or weekday mix, using 2 million real rows.
7 min read
CSV
Detecting Seasonality in a CSV of Daily Sales Data
Find weekly and monthly rhythms in daily sales from a CSV: a weekday index, autocorrelation at lag 7, what a flat result looks like and how to adjust for it.
6 min read
CSV
Cross Tabs From a CSV With SQL and a Chi Square Check
Build a cross tab of two CSV columns with DuckDB PIVOT, add row totals and percentages, and test with chi-square whether the two columns are really related.
7 min read
CSVGuide
More Analysis Moves for CSV Data You Can Use Today
Nine analysis moves for a CSV in SQL: cross tabs, period comparisons, concentration, seasonality, distribution shape, sampling, charts and reconciliation.
16 min read
JSONGuide
Event Analytics on JSON Properties in PostgreSQL Tested
A tested guide to analytics on JSON event data: envelope versus properties, funnels and retention, typed columns, indexes, type drift and backfills.
19 min read
Excel
Percentile Calculations Compared Across Excel and SQL
Compare Excel PERCENTILE.INC, PERCENTILE.EXC and MEDIAN with PostgreSQL percentile_cont and percentile_disc, with worked numbers.
6 min read
Excel
Splitting Text by Delimiter in Excel and SQL Queries
Split delimited text into columns or rows in Excel with TEXTSPLIT and Text to Columns and in PostgreSQL with split_part, string_to_array and unnest.
6 min read
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