100 articles tagged #Python
Getting 'database is locked' errors when multiple threads or processes write to the same SQLite file? This guide walks through every real fix — from timeout tuning to WAL mode — so your concurrent writes stop failing.
Your merge looked clean, but your row count is wrong and you have no idea why. This guide walks you through exactly how to diagnose silent row loss in pandas merge() — join types, key mismatches, duplicates, and more.
You merge cells with openpyxl, save the file, then reopen it in Excel only to find the data is gone. Here's exactly why it happens and how to write the merge correctly so the value survives every save.
You build a chart with openpyxl, save the workbook, open the file in Excel — and the chart is either blank or completely missing. Here's exactly why that happens and how to fix it for good.
openpyxl reads every row in a sheet by default — including hidden ones — but one common iteration pattern quietly skips them. Here's exactly why it happens and how to read all rows reliably.
Ran ALTER TABLE on your SQLite database and now your Python queries are returning wrong values or old column names? This is a classic schema-cache and cursor reuse problem — here's exactly how to fix it.
Copying rows between Excel workbooks with openpyxl looks straightforward until you notice fonts, fills, and borders vanishing silently. Learn exactly why styles get dropped and how to copy them reliably.
Getting "Excel xlsx file; not supported" after upgrading xlrd? Since xlrd 2.0 removed support for xlsx files, many Python scripts suddenly broke. Learn why this happens, how to fix it using openpyxl, and the best approaches for reading modern Excel files in Python.
You committed new rows to an SQLite database, queried it right after, and the old data came back. This is a classic isolation and connection-caching trap in Python's sqlite3 module — here's exactly how to fix it.
Run your Python sqlite3 script twice and suddenly your database has double the rows. This guide explains exactly why duplicates happen and gives you battle-tested strategies to stop them permanently.
You've set a number format in openpyxl, saved the file, opened it in Excel — and the cells still look plain. Here's exactly why that happens and how to fix it for currencies, dates, percentages, and more.
Async applications can appear responsive until a hidden deadlock causes tasks to wait forever. Learn how asyncio deadlocks happen, how to detect them early, and how to prevent application freezes in production.