second

src/main/java/com/example/practice/mapper/UserMapper.java

@@ -0,0 +1,20 @@
+package com.example.practice.mapper;
+
+import com.example.practice.entity.User;
+
+import java.util.List;
+
+public interface UserMapper {
+
+    List<User> selectAll();
+
+    User selectOne(Long id);
+
+    int insert(User user);
+
+    int update(User user);
+
+    int delete(Long id);
+
+}
+