Add a prototype of RegNoGenerator wich needs further tests

backend/src/main/java/ovh/herisson/Clyde/RegNoGenerator.java

@@ -0,0 +1,35 @@
+package ovh.herisson.Clyde;
+
+import org.hibernate.HibernateException;
+import org.hibernate.engine.jdbc.connections.spi.JdbcConnectionAccess;
+import org.hibernate.engine.spi.SessionImplementor;
+import org.hibernate.engine.spi.SharedSessionContractImplementor;
+import org.hibernate.id.IdentifierGenerator;
+
+import java.io.Serializable;
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+public class RegNoGenerator implements IdentifierGenerator {
+    @Override
+    public Object generate(SharedSessionContractImplementor session, Object object) {
+        try{
+            JdbcConnectionAccess jdbccon = session.getJdbcConnectionAccess();
+            Connection conn = jdbccon.obtainConnection();
+
+            Statement statement = conn.createStatement();
+            String query = "select count(reg_no)+1 from Users";
+
+            ResultSet set = statement.executeQuery(query);
+
+            if (set.next()){
+                return set.getLong(1)+1000;
+            }
+        } catch (SQLException e) {
+            throw new RuntimeException(e);
+        }
+        return null;
+    }
+}

backend/src/main/java/ovh/herisson/Clyde/Tables/User.java

@@ -1,6 +1,8 @@
 package ovh.herisson.Clyde.Tables;
 
 import jakarta.persistence.*;
+import org.hibernate.annotations.GenericGenerator;
+
 import java.util.Date;
 
 
@@ -8,7 +10,8 @@ import java.util.Date;
 @Table(name = "Users")
 public class User {
     @Id
-    @GeneratedValue(strategy = GenerationType.AUTO)
+    @GenericGenerator(name = "userGen", type = ovh.herisson.Clyde.RegNoGenerator.class)
+    @GeneratedValue(generator = "userGen")
     private Long regNo;
     private String lastName;
     private String firstName;