diff --git a/spring-security-oauth/src/main/java/org/baeldung/persistence/model/Post.java b/spring-security-oauth/src/main/java/org/baeldung/persistence/model/Post.java
index 767c6fbe78..045de363c3 100644
--- a/spring-security-oauth/src/main/java/org/baeldung/persistence/model/Post.java
+++ b/spring-security-oauth/src/main/java/org/baeldung/persistence/model/Post.java
@@ -2,6 +2,7 @@ package org.baeldung.persistence.model;
 
 import java.util.Date;
 
+import javax.persistence.Column;
 import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;
 import javax.persistence.GenerationType;
@@ -16,14 +17,18 @@ public class Post {
     @GeneratedValue(strategy = GenerationType.AUTO)
     private Long id;
 
+    @Column(nullable = false)
     private String title;
 
+    @Column(nullable = false)
     private String subreddit;
 
+    @Column(nullable = false)
     private String url;
 
     private boolean sendReplies;
 
+    @Column(nullable = false)
     private Date submissionDate;
 
     private boolean isSent;
@@ -31,7 +36,7 @@ public class Post {
     private String submissionResponse;
 
     @ManyToOne
-    @JoinColumn(name = "user_id")
+    @JoinColumn(name = "user_id", nullable = false)
     private User user;
 
     public Post() {
diff --git a/spring-security-oauth/src/main/java/org/baeldung/persistence/model/User.java b/spring-security-oauth/src/main/java/org/baeldung/persistence/model/User.java
index bcb9971fa5..ee941d10ed 100644
--- a/spring-security-oauth/src/main/java/org/baeldung/persistence/model/User.java
+++ b/spring-security-oauth/src/main/java/org/baeldung/persistence/model/User.java
@@ -1,13 +1,12 @@
 package org.baeldung.persistence.model;
 
 import java.util.Date;
-import java.util.List;
 
+import javax.persistence.Column;
 import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;
 import javax.persistence.GenerationType;
 import javax.persistence.Id;
-import javax.persistence.OneToMany;
 
 @Entity
 public class User {
@@ -16,6 +15,7 @@ public class User {
     @GeneratedValue(strategy = GenerationType.AUTO)
     private Long id;
 
+    @Column(nullable = false)
     private String username;
 
     private String accessToken;
@@ -26,9 +26,6 @@ public class User {
 
     private boolean needCaptcha;
 
-    @OneToMany(mappedBy = "user")
-    private List<Post> posts;
-
     public User() {
         super();
     }
@@ -81,14 +78,6 @@ public class User {
         this.needCaptcha = needCaptcha;
     }
 
-    public List<Post> getPosts() {
-        return posts;
-    }
-
-    public void setPosts(List<Post> posts) {
-        this.posts = posts;
-    }
-
     @Override
     public int hashCode() {
         final int prime = 31;