Add a MySQL connection tutorial.

Author: bgrainger

docs/content/tutorials/connect-to-mysql.md

@@ -0,0 +1,82 @@
+---
+date: 2019-11-18
+menu:
+  main:
+    parent: tutorials
+title: Connect to MySQL
+customtitle: How to Connect to MySQL from .NET Core
+weight: 3
+---
+
+# How to Connect to MySQL from .NET Core
+
+This tutorial will teach you how to connect to MySQL from .NET Core using C#.
+
+## 1. Install MySqlConnector
+
+First, install the [MySqlConnector NuGet package](https://www.nuget.org/packages/MySqlConnector/). From
+a command prompt, run:
+
+```
+dotnet add package MySqlConnector
+```
+
+Or right-click your project, choose **Manage NuGet Packages...**, in the **Search** box enter
+`MySqlConnector`, and install the package in your project.
+
+## 2. Connection String
+
+A typical connection string for MySQL is:
+
+```
+server=YOURSERVER;user=YOURUSERID;password=YOURPASSWORD;database=YOURDATABASE
+```
+
+Replace the values in that string with the appropriate settings for your database. For more advanced
+settings, see [Connection Options](/connection-options/).
+
+If you are using ASP.NET Core, your connection string will usually be stored in `appsettings.json`:
+
+```json
+{
+    ....
+    "ConnectionStrings": {
+        "Default": "server=YOURSERVER;user=YOURUSERID;password=YOURPASSWORD;database=YOURDATABASE"
+    }
+}
+```
+
+## 3. Configure Service (ASP.NET Core)
+
+If using ASP.NET Core, you will want to register a database connection in `Startup.cs`:
+
+```csharp
+public void ConfigureServices(IServiceCollection services)
+{
+    // ...
+    services.AddTransient<MySqlConnection>(_ => new MySqlConnection(Configuration["ConnectionStrings:Default"]));
+}
+```
+
+## 4. Open and Use the Connection
+
+In ASP.NET Core, the `MySqlConnection` object will be dependency-injected into your `Controller` class. For
+other kinds of projects, you may need to explicitly create the connection:
+
+```csharp
+using var connection = new MySqlConnection(yourConnectionString);
+```
+
+You can then open the connection and execute a query:
+
+```csharp
+await connection.OpenAsync();
+
+using var command = new MySqlCommand("SELECT field FROM table;", connection);
+using var reader = await command.ExecuteReaderAsync();
+while (await reader.ReadAsync())
+{
+    var value = reader.GetValue(0);
+    // do something with 'value'
+}
+```