diff --git a/bookstore/src/main/java/com/fjordtek/bookstore/model/Author.java b/bookstore/src/main/java/com/fjordtek/bookstore/model/Author.java
index 5b0ef44..da371e6 100644
--- a/bookstore/src/main/java/com/fjordtek/bookstore/model/Author.java
+++ b/bookstore/src/main/java/com/fjordtek/bookstore/model/Author.java
@@ -43,7 +43,11 @@ public class Author {
     private Long id;
 
 	//////////
-	@Column(name = "firstname", nullable = false)
+	@Column(
+			name = "firstname",
+			nullable = false,
+			columnDefinition = "NVARCHAR(" + strMax + ")"
+			)
 	@Size(
 			min = strMin, max = strMax,
 			message = "First name length must be " + strMin + "-" + strMax + " characters"
@@ -58,7 +62,11 @@ public class Author {
 	private String firstName;
 
 	//////////
-	@Column(name = "lastname", nullable = false)
+	@Column(
+			name = "lastname",
+			nullable = false,
+			columnDefinition = "NVARCHAR(" + strMax + ")"
+			)
 	@Size(
 			min = strMin, max = strMax,
 			message = "Last name length must be " + strMin + "-" + strMax + " characters"
@@ -74,14 +82,14 @@ public class Author {
 
 	// Omit from Jackson JSON serialization
 	//@JsonBackReference(value = "books")
-
 	@JsonIgnore
+
 	@OneToMany(
-			mappedBy     = "author",
-			// We consider EAGER FetchType for updatable tables, i.e. when adding new author
-			fetch        = FetchType.EAGER,
-			cascade      = CascadeType.ALL,
-			targetEntity = Book.class
+			mappedBy      = "author",
+			fetch         = FetchType.LAZY,
+			cascade       = CascadeType.ALL,
+			targetEntity  = Book.class
+			//orphanRemoval = true
 			)
 	private List<Book> books;
 
diff --git a/bookstore/src/main/java/com/fjordtek/bookstore/model/Book.java b/bookstore/src/main/java/com/fjordtek/bookstore/model/Book.java
index 67831c9..dea04c3 100644
--- a/bookstore/src/main/java/com/fjordtek/bookstore/model/Book.java
+++ b/bookstore/src/main/java/com/fjordtek/bookstore/model/Book.java
@@ -99,7 +99,10 @@ public class Book {
 	// Attributes with hard-coded constraints
 
 	//////////
-	@Column(nullable = false)
+	@Column(
+			nullable = false,
+			columnDefinition = "NVARCHAR(" + strMax + ")"
+			)
 	@Size(
 			min = strMin, max = strMax,
 			message = "Title length must be " + strMin + "-" + strMax + " characters"
@@ -139,7 +142,10 @@ public class Book {
 	// private Timestamp     year;
 	// ...
 	// TODO: Consider allowing 0 value if year is not known
-	@Column(nullable = true)
+	@Column(
+			nullable = false,
+			columnDefinition = "INT(4)"
+			)
 	@Min(
 			value   = yearMin,
 			message = "Minimum allowed year: " + yearMin
@@ -148,7 +154,10 @@ public class Book {
 	private int year;
 
 	//////////
-	@Column(unique  = true, nullable = false)
+	@Column(
+			unique  = true,
+			nullable = false
+			)
 	@NotBlank(
 			message = "Fill the ISBN code form"
 			)
diff --git a/bookstore/src/main/java/com/fjordtek/bookstore/model/BookHash.java b/bookstore/src/main/java/com/fjordtek/bookstore/model/BookHash.java
index 96201f1..4fc222c 100644
--- a/bookstore/src/main/java/com/fjordtek/bookstore/model/BookHash.java
+++ b/bookstore/src/main/java/com/fjordtek/bookstore/model/BookHash.java
@@ -75,7 +75,8 @@ public class BookHash {
 			name             = "hash_id",
 			unique           = true,
 			columnDefinition = "CHAR(32)",
-			updatable        = false
+			updatable        = false,
+			nullable         = false
 			)
 	private String hashId;
 
diff --git a/bookstore/src/main/java/com/fjordtek/bookstore/model/Category.java b/bookstore/src/main/java/com/fjordtek/bookstore/model/Category.java
index 7c3629c..b3ab1d9 100644
--- a/bookstore/src/main/java/com/fjordtek/bookstore/model/Category.java
+++ b/bookstore/src/main/java/com/fjordtek/bookstore/model/Category.java
@@ -5,6 +5,7 @@ package com.fjordtek.bookstore.model;
 import java.util.List;
 
 import javax.persistence.CascadeType;
+import javax.persistence.Column;
 import javax.persistence.Entity;
 import javax.persistence.FetchType;
 import javax.persistence.GeneratedValue;
@@ -34,12 +35,16 @@ public class Category {
 
 	////////////////////
 	// Attributes with hard-coded constraints
+	@Column(
+			nullable = false,
+			columnDefinition = "NVARCHAR(50)"
+			)
 	private String name;
 
 	// Omit from Jackson JSON serialization
 	//@JsonBackReference(value = "books")
-
 	@JsonIgnore
+
 	@OneToMany(
 			mappedBy     = "category",
 			fetch        = FetchType.LAZY,