Every .NET C# app that talks to MySQL starts with a connection string: one line that says where the server is, which database to use, who you are, and how to protect the connection. This guide builds one for Oracle's MySql.Data driver, which EF Core's MySql.EntityFrameworkCore provider also uses, explains each key with its documented default, and tests it with a small C# program that tells you exactly how it connected.
By default, every dotnet command uses the newest .NET SDK on the computer. That's fine until a teammate or a build server has a different one, and the same project starts behaving differently. A global.json file at the root of your repository settles which SDK the project uses. This guide creates one with .NET 10, then tries every rollForward value against the real SDK installed on this computer, so you can see which ones pass and which fail before you choose.
Before you create or build a C# project, it helps to know which .NET versions your computer has. One dotnet command answers each question: which SDK your project will use, which SDKs and runtimes are installed, and whether any of them needs an update. This guide runs each one on a Mac with .NET 10 and explains every line of output.
dotnet ef, the command-line tools for Entity Framework Core, is usually installed once for the whole computer. Installed as a local tool instead, it's pinned to an exact version in a small file inside your repository, so every developer and every build machine runs the same version as the project's EF Core packages. This guide installs it that way with .NET 10, shows every command's real output, and adds the one package the tools need in your project.
A table with a dozen columns doesn't fit in a terminal, and the mysql client's boxed output wraps into lines nobody can read. Ending the statement with \G instead of ; prints each row vertically, one column: value per line. This guide shows the difference on a real MySQL 9.7 table, and the client option that makes every result vertical.
A CHECK constraint is a rule MySQL enforces on every row, such as "a price can't be negative". When something refuses to save with ERROR 3819, or you just want to know which rules a database already has, you need to list them. MySQL keeps them in two INFORMATION_SCHEMA tables, and neither one has everything on its own. This guide joins them, on a real MySQL 9.7 database, and shows the quicker way for a single table.
A foreign key ties a column to another table: a product's CategoryId must be the Id of a real category. Before you delete a row, rename a table or change a column, you need to know which foreign keys are involved and what MySQL will do with them. This guide lists them three ways on a real MySQL 9.7 database: for one table, for the whole database, and in reverse, every table that points at a given one.
Indexes decide how fast MySQL can find rows, and which values must be unique. SHOW INDEX lists them for one table, and INFORMATION_SCHEMA.STATISTICS lists them for a whole database, ready to filter. This guide runs both on a real MySQL 9.7 database created by EF Core, and explains how to read multi-column indexes, where the order of the columns matters.
When you need to know exactly what a MySQL table looks like, which columns, which types, what can be empty and which keys exist, three statements answer at different levels of detail. DESCRIBE gives a quick table of columns, SHOW CREATE TABLE gives the complete definition with every index and constraint, and INFORMATION_SCHEMA.COLUMNS lets you query the answer. This guide runs all of them on a real MySQL 9.7 table created by EF Core.
The first thing to check in a MySQL database is which tables it has. SHOW TABLES answers that in one line, and INFORMATION_SCHEMA.TABLES adds the details: storage engine, collation, size and an approximate row count. This guide runs both against a real MySQL 9.7 database and explains the one number in there you shouldn't trust.
