diff --git a/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/controller/BookController.java b/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/controller/BookController.java
index 3b3636db..2f93c8c7 100644
--- a/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/controller/BookController.java
+++ b/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/controller/BookController.java
@@ -1,11 +1,17 @@
 package com.keploy.springbootpostgresgraphql.controller;
 
+import com.keploy.springbootpostgresgraphql.dto.AuthorInput;
+import com.keploy.springbootpostgresgraphql.dto.BookInput;
+import com.keploy.springbootpostgresgraphql.dto.CategoryInput;
 import com.keploy.springbootpostgresgraphql.entity.Author;
 import com.keploy.springbootpostgresgraphql.entity.Book;
+import com.keploy.springbootpostgresgraphql.entity.Category;
 import com.keploy.springbootpostgresgraphql.repository.AuthorRepository;
 import com.keploy.springbootpostgresgraphql.repository.BookRepository;
+import com.keploy.springbootpostgresgraphql.repository.CategoryRepository;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.graphql.data.method.annotation.Argument;
+import org.springframework.graphql.data.method.annotation.MutationMapping;
 import org.springframework.graphql.data.method.annotation.QueryMapping;
 import org.springframework.stereotype.Controller;
 
@@ -18,12 +24,19 @@ public class BookController {
     BookRepository bookRepository;
     @Autowired
     AuthorRepository authorRepository;
+    @Autowired
+    CategoryRepository categoryRepository;
 
     @QueryMapping
     public Book getBookByName(@Argument String name) {
         return bookRepository.findBookByName(name);
     }
 
+    @QueryMapping
+    public Book getBookById(@Argument int id) {
+        return bookRepository.findBookById(id);
+    }
+
     @QueryMapping
     public List<Book> getAllBooks() {
         return bookRepository.findAll();
@@ -39,5 +52,74 @@ public List<Author> getAllAuthors() {
         return authorRepository.findAll();
     }
 
+    @QueryMapping
+    public List<Category> getAllCategories() {
+        return categoryRepository.findAll();
+    }
+
+    @QueryMapping
+    public Category getCategoryById(@Argument int id) {
+        return categoryRepository.findCategoryById(id);
+    }
+
+    @MutationMapping
+    public Book addBook(@Argument BookInput book) {
+        Author author = authorRepository.findAuthorById(book.getAuthorId());
+        Book newBook = new Book();
+        newBook.setName(book.getName());
+        newBook.setPageCount(book.getPageCount());
+        newBook.setAuthor(author);
+        if (book.getCategoryId() != null) {
+            Category category = categoryRepository.findCategoryById(book.getCategoryId());
+            newBook.setCategory(category);
+        }
+        return bookRepository.save(newBook);
+    }
+
+    @MutationMapping
+    public Book updateBook(@Argument int id, @Argument BookInput book) {
+        Book existingBook = bookRepository.findBookById(id);
+        if (existingBook != null) {
+            Author author = authorRepository.findAuthorById(book.getAuthorId());
+            existingBook.setName(book.getName());
+            existingBook.setPageCount(book.getPageCount());
+            existingBook.setAuthor(author);
+            if (book.getCategoryId() != null) {
+                Category category = categoryRepository.findCategoryById(book.getCategoryId());
+                existingBook.setCategory(category);
+            } else {
+                existingBook.setCategory(null);
+            }
+            return bookRepository.save(existingBook);
+        }
+        return null;
+    }
+
+    @MutationMapping
+    public Boolean deleteBook(@Argument int id) {
+        bookRepository.deleteById(id);
+        return true;
+    }
 
+    @MutationMapping
+    public Author addAuthor(@Argument AuthorInput author) {
+        Author newAuthor = new Author();
+        newAuthor.setFirstName(author.getFirstName());
+        newAuthor.setLastName(author.getLastName());
+        return authorRepository.save(newAuthor);
+    }
+
+    @MutationMapping
+    public Boolean deleteAuthor(@Argument int id) {
+        authorRepository.deleteById(id);
+        return true;
+    }
+
+    @MutationMapping
+    public Category addCategory(@Argument CategoryInput category) {
+        Category newCategory = new Category();
+        newCategory.setName(category.getName());
+        newCategory.setDescription(category.getDescription());
+        return categoryRepository.save(newCategory);
+    }
 }
diff --git a/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/dto/AuthorInput.java b/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/dto/AuthorInput.java
new file mode 100644
index 00000000..c2d5e66e
--- /dev/null
+++ b/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/dto/AuthorInput.java
@@ -0,0 +1,13 @@
+package com.keploy.springbootpostgresgraphql.dto;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@AllArgsConstructor
+@NoArgsConstructor
+public class AuthorInput {
+    private String firstName;
+    private String lastName;
+}
diff --git a/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/dto/BookInput.java b/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/dto/BookInput.java
new file mode 100644
index 00000000..e0aba45b
--- /dev/null
+++ b/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/dto/BookInput.java
@@ -0,0 +1,15 @@
+package com.keploy.springbootpostgresgraphql.dto;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@AllArgsConstructor
+@NoArgsConstructor
+public class BookInput {
+    private String name;
+    private int pageCount;
+    private int authorId;
+    private Integer categoryId;
+}
diff --git a/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/dto/CategoryInput.java b/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/dto/CategoryInput.java
new file mode 100644
index 00000000..470c24ca
--- /dev/null
+++ b/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/dto/CategoryInput.java
@@ -0,0 +1,13 @@
+package com.keploy.springbootpostgresgraphql.dto;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@AllArgsConstructor
+@NoArgsConstructor
+public class CategoryInput {
+    private String name;
+    private String description;
+}
diff --git a/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/entity/Book.java b/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/entity/Book.java
index a84ce7b2..964068fe 100644
--- a/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/entity/Book.java
+++ b/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/entity/Book.java
@@ -25,5 +25,9 @@ public class Book {
     @JoinColumn(name = "author_id", nullable = false)
     private Author author;
 
+    @ManyToOne
+    @JoinColumn(name = "category_id")
+    private Category category;
+
 
 }
\ No newline at end of file
diff --git a/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/entity/Category.java b/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/entity/Category.java
new file mode 100644
index 00000000..35fb041f
--- /dev/null
+++ b/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/entity/Category.java
@@ -0,0 +1,28 @@
+package com.keploy.springbootpostgresgraphql.entity;
+
+import jakarta.persistence.*;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+import java.util.List;
+
+@Data
+@AllArgsConstructor
+@NoArgsConstructor
+@Entity
+@Table(name = "category")
+public class Category {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private int id;
+
+    @Column(nullable = false, unique = true)
+    private String name;
+
+    private String description;
+
+    @OneToMany(mappedBy = "category", cascade = CascadeType.ALL)
+    private List<Book> books;
+}
diff --git a/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/repository/BookRepository.java b/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/repository/BookRepository.java
index ba4eedc0..d9003192 100644
--- a/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/repository/BookRepository.java
+++ b/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/repository/BookRepository.java
@@ -11,6 +11,8 @@ public interface BookRepository extends JpaRepository<Book, Integer> {
 
     Book findBookByName(String name);
 
+    Book findBookById(int id);
+
     List<Book> findAll();
 
 }
diff --git a/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/repository/CategoryRepository.java b/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/repository/CategoryRepository.java
new file mode 100644
index 00000000..09aef201
--- /dev/null
+++ b/spring-boot-postgres-graphql/src/main/java/com/keploy/springbootpostgresgraphql/repository/CategoryRepository.java
@@ -0,0 +1,14 @@
+package com.keploy.springbootpostgresgraphql.repository;
+
+import com.keploy.springbootpostgresgraphql.entity.Category;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+import java.util.List;
+
+@Repository
+public interface CategoryRepository extends JpaRepository<Category, Integer> {
+    Category findCategoryById(int id);
+    Category findCategoryByName(String name);
+    List<Category> findAll();
+}
diff --git a/spring-boot-postgres-graphql/src/main/resources/graphql/schema.graphqls b/spring-boot-postgres-graphql/src/main/resources/graphql/schema.graphqls
index 5a5c47bc..cf94ce05 100644
--- a/spring-boot-postgres-graphql/src/main/resources/graphql/schema.graphqls
+++ b/spring-boot-postgres-graphql/src/main/resources/graphql/schema.graphqls
@@ -1,8 +1,37 @@
 type Query {
     getBookByName(name: String): Book
+    getBookById(id: ID!): Book
     getAllBooks: [Book]
     getAuthorById(id: Int): Author
     getAllAuthors: [Author]
+    getAllCategories: [Category]
+    getCategoryById(id: ID!): Category
+}
+
+type Mutation {
+    addBook(book: BookInput!): Book
+    updateBook(id: ID!, book: BookInput!): Book
+    deleteBook(id: ID!): Boolean
+    addAuthor(author: AuthorInput!): Author
+    deleteAuthor(id: ID!): Boolean
+    addCategory(category: CategoryInput!): Category
+}
+
+input BookInput {
+    name: String!
+    pageCount: Int!
+    authorId: Int!
+    categoryId: Int
+}
+
+input AuthorInput {
+    firstName: String!
+    lastName: String!
+}
+
+input CategoryInput {
+    name: String!
+    description: String
 }
 
 type Book {
@@ -10,10 +39,18 @@ type Book {
     name: String
     pageCount: Int
     author: Author
+    category: Category
 }
 
 type Author {
     id: ID
     firstName: String
     lastName: String
+}
+
+type Category {
+    id: ID
+    name: String
+    description: String
+    books: [Book]
 }
\ No newline at end of file