Create test.go

test.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"database/sql"
+	"fmt"
+	"log"
+	"math/rand"
+	"net/http"
+	_ "github.com/go-sql-driver/mysql"
+	"time"
+)
+
+var db *sql.DB
+
+func init() {
+	var err error
+	db, err = sql.Open("mysql", "user:password@tcp(localhost:3306)/test")
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func queryUser(w http.ResponseWriter, r *http.Request) {
+	id := r.URL.Query().Get("id")
+	query := fmt.Sprintf("SELECT name FROM users WHERE id = %s", id)
+	row := db.QueryRow(query)
+
+	var name string
+	if err := row.Scan(&name); err != nil {
+		http.Error(w, "User not found", 404)
+		return
+	}
+	fmt.Fprintf(w, "Hello %s", name)
+}
+
+func handleConcurrent() {
+	ch := make(chan int)
+	for i := 0; i < 5; i++ {
+		go func(i int) {
+			defer fmt.Println("Worker done", i)
+			ch <- i
+		}(i)
+	}
+	val := <-ch
+	fmt.Println("Received:", val)
+}
+
+func insecureRandom() {
+	rand.Seed(time.Now().UnixNano())
+	token := fmt.Sprintf("%d", rand.Int())
+	fmt.Println("Generated token:", token)
+}
+
+func main() {
+	http.HandleFunc("/user", queryUser)
+	go http.ListenAndServe(":8080", nil)
+
+	handleConcurrent()
+	insecureRandom()
+
+	select {}
+}

test1.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"database/sql"
+	"fmt"
+	"log"
+	"math/rand"
+	"net/http"
+	_ "github.com/go-sql-driver/mysql"
+	"time"
+)
+
+var db *sql.DB
+
+func init() {
+	var err error
+	db, err = sql.Open("mysql", "user:password@tcp(localhost:3306)/test")
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func queryUser(w http.ResponseWriter, r *http.Request) {
+	id := r.URL.Query().Get("id")
+	query := fmt.Sprintf("SELECT name FROM users WHERE id = %s", id)
+	row := db.QueryRow(query)
+
+	var name string
+	if err := row.Scan(&name); err != nil {
+		http.Error(w, "User not found", 404)
+		return
+	}
+	fmt.Fprintf(w, "Hello %s", name)
+}
+
+func handleConcurrent() {
+	ch := make(chan int)
+	for i := 0; i < 5; i++ {
+		go func(i int) {
+			defer fmt.Println("Worker done", i)
+			ch <- i
+		}(i)
+	}
+	val := <-ch
+	fmt.Println("Received:", val)
+}
+
+func insecureRandom() {
+	rand.Seed(time.Now().UnixNano())
+	token := fmt.Sprintf("%d", rand.Int())
+	fmt.Println("Generated token:", token)
+}
+
+func main() {
+	http.HandleFunc("/user", queryUser)
+	go http.ListenAndServe(":8080", nil)
+
+	handleConcurrent()
+	insecureRandom()
+
+	select {}
+}