init.

db.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"context"
+	"database/sql"
+	"log"
+	"os"
+)
+
+func openDB() (*sql.DB, error) {
+	dsn := os.Getenv("MYSQL_DSN")
+	if dsn == "" {
+		log.Fatal("MYSQL_DSN is empty!")
+	}
+	return sql.Open("mysql", dsn)
+}
+
+func migrate(ctx context.Context, db *sql.DB) error {
+	ddl := `
+CREATE TABLE IF NOT EXISTS students (
+  id BIGINT PRIMARY KEY AUTO_INCREMENT,
+  name VARCHAR(100) NOT NULL,
+  age INT NOT NULL,
+  email VARCHAR(255) NOT NULL UNIQUE,
+  created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;`
+	_, err := db.ExecContext(ctx, ddl)
+	return err
+}