To design a Golang REST API that interacts with a MySQL database to perform CRUD operations on a "Product" entity, you'll need to follow these steps:

1. Set up the Go environment and create a new project
2. Install required packages for handling HTTP requests and connecting to MySQL
3. Create a Product struct to represent the Product entity
4. Connect to the MySQL database
5. Implement functions for each CRUD operation (Create, Read, Update, Delete)
6. Set up routes for each endpoint and handle user input validation

Here's an example implementation of this REST API:

```go
package main

import (
	"encoding/json"
	"fmt"
	"github.com/gorilla/mux"
	_ "github.com/go-sql-driver/mysql"
	"net/http"
	"strconv"
)

type Product struct {
	ID          int    `json:"id"`
	Name        string `json:"name"`
	Description string `json:"description"`
	Price       float64  `json:"price"`
}

var products []Product

func main() {
	router := mux.NewRouter()
	router.HandleFunc("/products", getProducts).Methods("GET")
	router.HandleFunc("/product/{id}", getProduct).Methods("GET")
	router.HandleFunc("/product", createProduct).Methods("POST")
	router.HandleFunc("/product/{id}", updateProduct).-Methods("PUT")
	router.HandleFunc("/product/{id}", deleteProduct).Methods("DELETE")

	http.ListenAndServe(":8000", router)
}

func getProducts(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(products)
}

func getProduct(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	params := mux.Vars(r)
	id, err := strconv.Atoi(params["id"])
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		return
	}
	for _, product := range products {
		if product.ID == id {
			json.NewEncoder(w).Encode(product)
			return
		}
	}
	w.WriteHeader(http.StatusNotFound)
}

func createProduct(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	var newProduct Product
	err := json.NewDecoder(r.Body).Decode(&newProduct)
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		return
	}
	newProduct.ID = len(products) + 1
	products = append(products, newProduct)
	json.NewEncoder(w).Encode(newProduct)
}

func updateProduct(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	params := mux.Vars(r)
	id, err := strconv.Atoi(params["id"])
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		return
	}
	var updatedProduct Product
	err = json.NewDecoder(r.Body).Decode(&updatedProduct)
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		return
	}
	for i, product := range products {
		if product.ID == id {
			products[i] = updatedProduct
			json.NewEncoder(w).Encode(updatedProduct)
			return
		}
	}
	w.WriteHeader(http.StatusNotFound)
}

func deleteProduct(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	params := mux.Vars(r)
	id, err := strconv.Atoi(params["id"])
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		return
	}
	for i, product := range products {
		if product.ID == id {
			products = append(products[:i], products[i+1:]...)
			break
		}
	}
	json.NewEncoder(w).Encode(products)
}
```

This example uses the Gorilla Mux package for routing and the Go MySQL driver to connect to a MySQL database. You'll need to replace the in-memory `products` slice with actual database queries using the `database/sql` package.

Remember to add proper error handling, input validation, and response codes for each endpoint.
Product" 엔티티에 대해 CRUD 작업을 수행하기 위해 MySQL 데이터베이스와 상호 작용하는 Golang REST API를 설계하려면 다음 단계를 따라야 합니다.

1. Go 환경을 설정하고 새 프로젝트를 생성합니다
2. HTTP 요청을 처리하고 MySQL에 연결하기 위해 필요한 패키지를 설치합니다
3. Product 엔티티를 나타내는 Product 구조체를 생성합니다
4. MySQL 데이터베이스에 연결
5. 각 CRUD 작업(생성, 읽기, 업데이트, 삭제)에 대한 함수를 구현합니다
6. 각 엔드포인트에 대한 경로를 설정하고 사용자 입력 유효성 검사를 처리합니다

이 REST API의 구현 예는 다음과 같습니다:

```go
package main

import (
	"encoding/json"
	"fmt"
	"github.com/gorilla/mux"
	_ "github.com/go-sql-driver/mysql"
	"net/http"
	"strconv"
)

type Product struct {
	ID          int    `json:"id"`
	Name        string `json:"name"`
	Description string `json:"description"`
	Price       float64  `json:"price"`
}

var products []Product

func main() {
	router := mux.NewRouter()
	router.HandleFunc("/products", getProducts).Methods("GET")
	router.HandleFunc("/product/{id}", getProduct).Methods("GET")
	router.HandleFunc("/product", createProduct).Methods("POST")
	router.HandleFunc("/product/{id}", updateProduct).-Methods("PUT")
	router.HandleFunc("/product/{id}", deleteProduct).Methods("DELETE")

	http.ListenAndServe(":8000", router)
}

func getProducts(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(products)
}

func getProduct(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	params := mux.Vars(r)
	id, err := strconv.Atoi(params["id"])
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		return
	}
	for _, product := range products {
		if product.ID == id {
			json.NewEncoder(w).Encode(product)
			return
		}
	}
	w.WriteHeader(http.StatusNotFound)
}

func createProduct(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	var newProduct Product
	err := json.NewDecoder(r.Body).Decode(&newProduct)
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		return
	}
	newProduct.ID = len(products) + 1
	products = append(products, newProduct)
	json.NewEncoder(w).Encode(newProduct)
}

func updateProduct(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	params := mux.Vars(r)
	id, err := strconv.Atoi(params["id"])
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		return
	}
	var updatedProduct Product
	err = json.NewDecoder(r.Body).Decode(&updatedProduct)
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		return
	}
	for i, product := range products {
		if product.ID == id {
			products[i] = updatedProduct
			json.NewEncoder(w).Encode(updatedProduct)
			return
		}
	}
	w.WriteHeader(http.StatusNotFound)
}

func deleteProduct(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	params := mux.Vars(r)
	id, err := strconv.Atoi(params["id"])
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		return
	}
	for i, product := range products {
		if product.ID == id {
			products = append(products[:i], products[i+1:]...)
			break
		}
	}
	json.NewEncoder(w).Encode(products)
}
```

이 예제에서는 라우팅을 위해 Gorilla Mux 패키지를 사용하고 MySQL 데이터베이스에 연결하기 위해 Go MySQL 드라이버를 사용합니다. `database/sql` 패키지를 사용하여 인메모리 `products` 슬라이스를 실제 데이터베이스 쿼리로 대체해야 합니다.

각 엔드포인트에 대해 적절한 오류 처리, 입력 유효성 검사 및 응답 코드를 추가해야 합니다.