EF Core names each table after your DbSet property: Products, Categories. On SQL Server or Windows that's harmless, but MySQL on Linux and in Docker compares table names case-sensitively, so products and Products are different tables and hand-written SQL breaks. This guide sets lowercase names with ToTable, shows the rename migration EF Core generates for an existing database, and the SQL MySQL actually runs.

What should happen to a category's products when the category is deleted? EF Core answers for you, unless you answer first: for a required relationship, its default is to delete the products too, silently. This guide shows that default happening in MySQL, switches it to Restrict so the database refuses instead, and shows the two different errors you get afterwards, one from MySQL and one from EF Core itself.

Every EF Core rule you add, a table name, a maximum length, an index, a constraint, goes into OnModelCreating by default, and that method grows until nobody wants to touch it. IEntityTypeConfiguration<T> gives each entity its own small class instead. This guide moves a real configuration into such classes, registers them all with one line, and proves the move changed nothing in the database model.

The most common query on a history table is "this item's entries, newest first". An index on just the item's Id finds the rows, but MySQL then has to sort them. An index on the Id and the time does both jobs. This guide creates one from EF Core's model, explains why the order of its columns decides what it can speed up, fixes the migration order MySQL needs, and uses EXPLAIN to prove the index is used.

Some values must never repeat: a product's SKU, a category's name, a user's email. Checking in code isn't enough, because two requests at the same moment can both pass the check. A unique index makes the database refuse the second one. This guide adds two from EF Core's model, applies them to MySQL 9.7, and shows what MySQL treats as a duplicate, which isn't always what you'd expect.

Validation in your API stops most bad data, but not data from a script, a second app, or a bug that skips the validation. A CHECK constraint makes the database itself refuse a row that breaks a rule, such as a negative price. This guide adds three to a products table from EF Core's model, applies them with a migration, and proves MySQL enforces them on both inserts and updates.

You save DateTime.UtcNow with EF Core, read it back from MySQL, and the Z that marks UTC is gone from your API's JSON. Worse, a DateTime.Now slipped in somewhere is stored as local time, hours away from everything else. This guide shows both problems with a real .NET C# Web API and MySQL 9.7, explains why they happen, and fixes them for every DateTime in the model with one small value converter.

Money belongs in a decimal, never a double, and the database column needs a precision you chose on purpose. This guide shows what MySQL column EF Core creates for a decimal when you don't configure it, how MySQL handles values that don't fit, and the three ways to set the precision: one property, an attribute, or one rule for every decimal in the model.

By default, EF Core saves a C# enum as its number: Sale becomes 2. That works, but anyone reading the table needs the C# code to know what 2 means, and reordering the enum silently changes the meaning of every old row. This guide stores enums as their names instead, first for one property and then for every enum at once, and handles the part most guides skip: the rows that already hold numbers.

Until .NET 10, even a three-line C# program needed a project file. Now dotnet run hello.cs runs a single .cs file directly, and a line at the top can pull in NuGet packages. It's perfect for small tools and quick tests, like checking that a database connection string works. This guide writes one, adds a package, shows where .NET builds it, and turns it into a normal project when it outgrows one file.