Add mysql cookbook

_cookbook/code/mysql-db/app.cr

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+require "kemal"
+require "db"
+require "mysql"
+
+# Initialize a single DB connection
+DB_URL = "mysql://root:password@localhost:3306/mydb"
+DB = DB.open(DB_URL)
+
+# Example User model
+class User
+  property id : Int32
+  property name : String
+  property email : String
+
+  def initialize(@id, @name, @email)
+  end
+end
+
+# List all users
+get "/users" do |env|
+  # Initialize empty array to store User objects
+  users = [] of User
+
+  # Query database for all users
+  DB.query "SELECT * FROM users" do |rs|
+    # For each row in result set
+    rs.each do
+      # Create new User object from row data and add to array
+      users << User.new(
+        id: rs.read(Int32),    # Read id column as Integer
+        name: rs.read(String), # Read name column as String 
+        email: rs.read(String) # Read email column as String
+      )
+    end
+  end
+
+  # Return users array as JSON response
+  users.to_json
+end
+
+# Create a new user
+post "/users" do |env|
+  name = env.params.json["name"].as(String)
+  email = env.params.json["email"].as(String)
+
+  user_id = DB.exec "INSERT INTO users (name, email) VALUES (?, ?) RETURNING id", name, email do |rs|
+    rs.each { return rs.read(Int32) }
+  end
+
+  {message: "User created with id: #{user_id}"}.to_json
+end
+
+# Delete a user
+delete "/users/:id" do |env|
+  id = env.params.url["id"].to_i
+
+  # Delete user and check if any rows were affected
+  result = DB.exec "DELETE FROM users WHERE id = ?", id
+
+  if result.rows_affected > 0
+    {message: "User deleted successfully"}.to_json
+  else
+    env.response.status_code = 404
+    {message: "User not found"}.to_json
+  end
+end
+
+Kemal.run

_cookbook/mysql-db.md

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+---
+layout: doc
+title: MySQL DB Recipe
+---
+
+Add the `mysql` shard to your `shard.yml` file.
+
+```yaml
+dependencies:
+  mysql:
+    github: crystal-lang/crystal-mysql
+```
+
+```ruby
+{% include_relative code/mysql-db/app.cr %}
+```
+
+[Source Code](https://github.com/kemalcr/kemalcr.com/tree/master/_cookbook/code/mysql-db)