Databases, Data Modeling, and Data Access
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You don't need to install MySQL to use it. With Docker Desktop, one small compose.yaml file runs the official MySQL 9.7 image with its data stored safely in a volume, and one command starts it. This guide builds that file line by line, starts MySQL for the first time, and shows exactly what to look for in the output.
I ran SHOW PROCESSLIST in MySQL 9.7 to see who was connected, and the result ended with 1 warning. SHOW WARNINGS named it: Warning 1287, the old implementation behind SHOW PROCESSLIST is deprecated. Querying the Performance Schema's processlist table directly gives the same list, without the warning.
I changed a password in my .env file, restarted MySQL with Docker Compose, and MySQL rejected the new password with ERROR 1045 (28000): Access denied. The container had the new value, but MySQL was still expecting the old one. This post shows why that happens with the official MySQL image, and how I fixed it without deleting any data.
I typed SELECT 'café' into the mysql client inside the official MySQL Docker container, and the client showed 'caf'. The é never appeared on screen and never reached MySQL, and there was no error at all. The container runs without a locale, so the client only accepts plain ASCII. One extra flag on docker compose exec fixes it.
Entity Framework Core maps each database table to an entity class and gives you a DbContext to query them. Most of the time you read from a single DbSet, but sooner or later you need data that lives across two tables — exactly what a SQL JOIN gives you. In EF Core, the lambda-based Join() method does the same job, and it translates into real SQL that runs on the database server.
Everything below targets .NET 10 and EF Core 10, the current Long Term Support releases.
