YAML
Using DuckDB to Query Data Stored as YAML With read_yaml
Install DuckDB's yaml community extension and query YAML files with read_yaml: inferred types, nested structs, unnest, globs, mixed types and broken files.
6 min read
Library
Everything you need to level up your coding skills.
CSV
Writing CSV From an Array of Objects in JavaScript
Turn an array of objects into CSV in JavaScript by hand or with csv-stringify: quoting, dates, booleans, formulas, BOM and a streaming writer.
9 min read
XML
Reading Excel XML Spreadsheet 2003 Files With Python
The old Excel XML Spreadsheet 2003 format is plain XML with Worksheet, Row, Cell and Data elements. Read it with lxml, handle Index gaps and types.
7 min read
Excel
Building Cohort Tables From an Excel Export With SQL
Turn an Excel export of orders into a cohort retention table with SQL: first purchase month, months since, a retention triangle and honest recent cohorts.
7 min read
JSON
Reading JSON in SQL Server With OPENJSON and a Schema
How OPENJSON turns a JSON array or object into rows in SQL Server, with the default key, value and type columns, the WITH clause, nested arrays and the traps.
7 min read
CSV
Streaming a Huge CSV Into a Database From Node the Fast Way
Load 2,000,000 CSV rows into PostgreSQL and SQLite from Node and compare per-row inserts, batches, transactions and COPY, with timings and failure behavior.
10 min read
Excel
Building a Forecast Baseline From Excel History in SQL
Build simple forecast baselines from monthly history in SQL: last value, seasonal naive, moving average and linear trend, and test them on held out months.
7 min read
CSV
Converting CSV to JSON in Node With a Few Lines of Code
Convert a CSV to JSON or NDJSON in Node with csv-parse, keep ZIP codes as text, and stream 2,000,000 rows at 120 MB instead of 1.6 GB.
8 min read
XML
Flattening Hierarchical XML for Excel Users With Python
Turn orders with repeating items into a workbook a spreadsheet user can filter: one sheet per level linked by order id, or one wide sheet, plus the checks.
6 min read
YAML
Flattening Nested YAML Into Rows of Path and Value
Turn a nested YAML document into path, type and value rows with a short recursive generator, then load the rows into SQL to search and compare configs.
6 min read
Excel
Finding Duplicates and Gaps in an Excel Sheet With SQL
Use SQL on an Excel sheet to find repeated keys, missing numbers in a sequence and missing dates with GROUP BY, window functions and gaps and islands.
7 min read
CSV
Why Splitting CSV by Comma in JavaScript Goes Wrong
line.split(',') breaks on quoted commas, quotes, line breaks and CRLF. See the failures, why the regex fix is slow, and a 30 line parser that works.
7 min read
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