This guide walks you through downloading and installing the DM (达梦) database, creating databases, using the client, mastering basic and advanced SQL syntax, comparing it with MySQL, Oracle, and SQL Server, and highlights its performance, security, and compatibility features.
This tutorial demonstrates how to import pandas, create a sample DataFrame, and apply the DataFrame.query method with SQL‑like expressions—including basic, multiple, OR, IN, NOT IN, variable, and isin conditions—to filter data efficiently.
The article recounts a legacy project that relied on MySQL 5.6, explains common pitfalls of that version such as replication lag, heavy performance_schema overhead, binlog issues, and memory limits, then details why an upgrade to 5.7 was rolled back due to syntax changes, case‑sensitivity differences, and unresolved configuration problems.
A developer noticed an UPDATE statement that appeared to run without effect, discovered that using AND between column assignments is invalid in MySQL, learned the correct comma‑separated syntax, and saw how logical AND expressions can produce unexpected zero values.
This article explains why a MySQL UPDATE statement can appear to have no effect when using AND between assignments, shows the correct comma‑separated syntax, and provides visual verification of the fix.
The article explains a common MySQL UPDATE mistake where developers use AND between column assignments, shows the unexpected result of owner_code becoming 0, analyzes the logical expression behind it, and provides the correct comma‑separated syntax to reliably update multiple fields.
This article explains why a syntactically correct MySQL UPDATE statement may seem ineffective, demonstrates the difference between using commas and the AND operator for multi‑column updates, and provides the proper syntax to ensure the intended rows are modified.
