Merge pull request #43 from WangGithub0/issue-41

change the customer id generation strategy

JtProject/src/main/java/com/jtspringproject/JtSpringProject/models/User.java

@@ -15,7 +15,7 @@
 public class User {
 
 	@Id
-	@GeneratedValue(strategy=GenerationType.AUTO)
+	@GeneratedValue(strategy=GenerationType.IDENTITY)
 	private int id;
 
 	@Column(unique = true)

JtProject/src/main/java/com/jtspringproject/JtSpringProject/services/userService.java

@@ -4,6 +4,7 @@
 import java.util.List;
 
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.dao.DataIntegrityViolationException;
 import org.springframework.stereotype.Service;
 
 import com.jtspringproject.JtSpringProject.dao.userDao;
@@ -19,7 +20,12 @@ public List<User> getUsers(){
 	}
 
 	public User addUser(User user) {
-		return this.userDao.saveUser(user);
+		try {
+			return this.userDao.saveUser(user);
+		} catch (DataIntegrityViolationException e) {
+			// handle unique constraint violation, e.g., by throwing a custom exception
+			throw new RuntimeException("Add user error");
+		}
 	}
 
 	public User checkLogin(String username,String password) {

README.md

@@ -29,8 +29,10 @@
 
 ### Database
 
-MySQL or MariaDB can be used as the database for this project. The database connection can be configured in the `application.properties` file, with the appropriate values for the following properties:
-(you'd better use another username not root)
+MySQL or MariaDB can be used as the database for this project. The database connection can be configured in the `src/main/resources/application.properties` file, with the appropriate values for the following properties:
+
+**( You'd better use another username not root, and ensure that the user has the corresponding permissions for the database. )**
+
 ```properties
     db.url=jdbc:mysql://[ip address of db]:[port of db]/ecommjava?createDatabaseIfNotExist=true
     db.username=[username]