JSONGuide
Using jq to Slice Up JSON in the Terminal Reliably
A tested guide to jq 1.8 for slicing JSON in the terminal: filters, streams, CSV, grouping, logs, safe variables, in-place edits and number quirks.
17 min read
Tag
how-to
590 posts
Excel
Writing Conditional Formatting From Code in Workbooks
Write Excel conditional formatting from Python with XlsxWriter or openpyxl: value rules, color scales, data bars and formula rules, with tests.
7 min read
CSV
Validating a CSV File Against a Lookup Table With SQL
Find CSV values missing from a lookup table with an anti-join, keep line numbers right, avoid the NOT IN trap with NULLs and see a foreign key's error.
10 min read
Excel
Sending Charts From a Query to an Excel Sheet by Script
Send charts from a SQL query to an Excel sheet by script: write the data, add a native chart with XlsxWriter or openpyxl, size it and label it.
7 min read
JSON
JSON parse and stringify Options You Probably Missed
The extra arguments of JSON.stringify and JSON.parse, tested in Node 24: toJSON, replacer arrays, indent limits, call order and exact numbers.
9 min read
CSV
Checking That Every Date in a CSV File Parses Correctly
Check every date in a CSV with a strict parse and a round trip, then ranges. strptime accepted 2025-3-4, DuckDB cast kept the date of 2025-03-14 10:30.
10 min read
Excel
Designing a Report Query Before Touching Excel at All
Design a report query before opening Excel: fix the grain, avoid join fan-out, put rules in SQL, bind parameters and test totals against a trusted number.
8 min read
PostgreSQL
Reading BUFFERS Output in EXPLAIN for PostgreSQL Queries
Read the BUFFERS output in PostgreSQL EXPLAIN: shared hit, read, dirtied and written, temp blocks, I/O timing, and what the numbers say about cache and disk.
7 min read
CSV
Finding Duplicate Keys in a CSV File Before an Import
Find repeated ids in a CSV before a primary key rejects the load, with SQL, pandas and uniq -d, line numbers and an exact versus conflicting split.
9 min read
JSONGuide
JSON in JavaScript and Node Done Carefully and Correctly
A tested guide to JSON in JavaScript and Node 24: what stringify drops, parse errors, big numbers, dates, circular data, cloning, files and large inputs.
20 min read
ExcelGuide
Building Excel Reports From SQL Queries People Trust
Build Excel reports from SQL that readers trust: design the query, write sheets, formats and charts from code, check totals, version the query, schedule it.
18 min read
CSV
Validating CSV Columns With Python and pydantic Models
Validate each CSV row against a pydantic model with types, literals, patterns and a cross-field rule: 193,708 rows in 0.95 s, with file line numbers.
10 min read