diff --git a/dmp-backend/data/src/main/java/eu/eudat/data/entities/DataRepository.java b/dmp-backend/data/src/main/java/eu/eudat/data/entities/DataRepository.java
index 075326ac7..81ad45035 100644
--- a/dmp-backend/data/src/main/java/eu/eudat/data/entities/DataRepository.java
+++ b/dmp-backend/data/src/main/java/eu/eudat/data/entities/DataRepository.java
@@ -26,14 +26,14 @@ public class DataRepository implements Serializable, DataEntity<DataRepository,
 	@Column(name = "\"Abbreviation\"")
 	private String abbreviation;
 
-	@Column(name = "\"Reference\"", nullable = false)
+	@Column(name = "\"Reference\"")
 	private String reference;
 
 	@Column(name = "\"Uri\"")
 	private String uri;
 
 	@Type(type = "eu.eudat.configurations.typedefinition.XMLType")
-	@Column(name = "\"Definition\"", columnDefinition = "xml", nullable = true)
+	@Column(name = "\"Definition\"", columnDefinition = "xml")
 	private String definition;
 
 	@OneToMany(mappedBy = "dataRepository", cascade = CascadeType.ALL, orphanRemoval = true)
@@ -42,14 +42,14 @@ public class DataRepository implements Serializable, DataEntity<DataRepository,
 	@Column(name = "\"Status\"", nullable = false)
 	private Short status;
 
-	@Column(name = "\"Created\"")
+	@Column(name = "\"Created\"", nullable = false)
 	private Date created = null;
 
-	@Column(name = "\"Modified\"")
+	@Column(name = "\"Modified\"", nullable = false)
 	private Date modified = new Date();
 
 	@ManyToOne(fetch = FetchType.LAZY)
-	@JoinColumn(name = "\"CreationUser\"", nullable = true)
+	@JoinColumn(name = "\"CreationUser\"")
 	private UserInfo creationUser;
 
 
diff --git a/dmp-backend/data/src/main/java/eu/eudat/data/entities/Dataset.java b/dmp-backend/data/src/main/java/eu/eudat/data/entities/Dataset.java
index 41081cefb..4692571b0 100644
--- a/dmp-backend/data/src/main/java/eu/eudat/data/entities/Dataset.java
+++ b/dmp-backend/data/src/main/java/eu/eudat/data/entities/Dataset.java
@@ -92,7 +92,7 @@ public class Dataset implements DataEntity<Dataset, UUID> {
 	@Column(name = "\"ID\"", updatable = false, nullable = false, columnDefinition = "BINARY(16)")
 	private UUID id;
 
-	@Column(name = "\"Label\"")
+	@Column(name = "\"Label\"", nullable = false)
 	private String label;
 
 	@ManyToOne(fetch = FetchType.LAZY)
@@ -104,16 +104,16 @@ public class Dataset implements DataEntity<Dataset, UUID> {
 	private String uri;
 
 	@Type(type = "eu.eudat.configurations.typedefinition.XMLType")
-	@Column(name = "\"Properties\"", columnDefinition = "xml", nullable = true)
+	@Column(name = "\"Properties\"", columnDefinition = "xml")
 	private String properties;
 
 	@ManyToOne(fetch = FetchType.LAZY)
 	//@Cascade(value=org.hibernate.annotations.CascadeType.ALL)
-	@JoinColumn(name = "\"Profile\"", nullable = true)
+	@JoinColumn(name = "\"Profile\"")
 	private DatasetProfile profile;
 
 	@Type(type = "eu.eudat.configurations.typedefinition.XMLType")
-	@Column(name = "\"Reference\"", columnDefinition = "xml", nullable = true)
+	@Column(name = "\"Reference\"", columnDefinition = "xml")
 	private String reference;
 
 	@OneToMany(fetch = FetchType.LAZY)
@@ -136,16 +136,16 @@ public class Dataset implements DataEntity<Dataset, UUID> {
 	private Short status;
 
 
-	@Column(name = "\"Created\"")
+	@Column(name = "\"Created\"", nullable = false)
 	@Convert(converter = DateToUTCConverter.class)
 	private Date created = null;
 
-	@Column(name = "\"Modified\"")
+	@Column(name = "\"Modified\"", nullable = false)
 	@Convert(converter = DateToUTCConverter.class)
 	private Date modified = new Date();
 
 	@ManyToOne(fetch = FetchType.LAZY)
-	@JoinColumn(name = "\"Creator\"", nullable = true)
+	@JoinColumn(name = "\"Creator\"")
 	private UserInfo creator;
 
 	@Column(name = "\"Description\"")
diff --git a/dmp-backend/data/src/main/java/eu/eudat/data/entities/DatasetProfile.java b/dmp-backend/data/src/main/java/eu/eudat/data/entities/DatasetProfile.java
index 7b7aa11c4..a11316abd 100644
--- a/dmp-backend/data/src/main/java/eu/eudat/data/entities/DatasetProfile.java
+++ b/dmp-backend/data/src/main/java/eu/eudat/data/entities/DatasetProfile.java
@@ -49,7 +49,7 @@ public class DatasetProfile implements DataEntity<DatasetProfile,UUID>{
     @Column(name = "\"ID\"", updatable = false, nullable = false, columnDefinition = "BINARY(16)")
     private UUID id;
 
-    @Column(name = "\"Label\"")
+    @Column(name = "\"Label\"", nullable = false)
     private String label;
 
     @OneToMany(fetch = FetchType.LAZY, mappedBy = "profile")