diff --git a/src/main/resources/Group.hbm.xml b/src/main/resources/Group.hbm.xml
index ea83ccd..e73bee2 100644
--- a/src/main/resources/Group.hbm.xml
+++ b/src/main/resources/Group.hbm.xml
@@ -15,8 +15,8 @@
     <class name="Group" table="GROUPS">
         <id name="gId" column="GID">
         </id>
-        <property name="uri" column="URI"/>
-        <property name="name" column="NAME"/>
+        <property name="uri" column="URI" not-null="true"/>
+        <property name="name" column="NAME" not-null="true"/>
         <set name = "requests" cascade="all">
             <key column = "GID" not-null="false"/>
             <one-to-many class="Request"/>
diff --git a/src/main/resources/Password.hbm.xml b/src/main/resources/Password.hbm.xml
index 23a2b31..bff9873 100644
--- a/src/main/resources/Password.hbm.xml
+++ b/src/main/resources/Password.hbm.xml
@@ -14,7 +14,7 @@
 
     <class name="Password" table="PW">
         <id name="uId" column="UID"/>
-        <property name="pw" column="PW"/>
+        <property name="pw" column="PW" not-null="true"/>
     </class>
 
 </hibernate-mapping>
\ No newline at end of file
diff --git a/src/main/resources/Request.hbm.xml b/src/main/resources/Request.hbm.xml
index 514de7c..010d45a 100644
--- a/src/main/resources/Request.hbm.xml
+++ b/src/main/resources/Request.hbm.xml
@@ -15,13 +15,13 @@
     <class name="Request" table="REQUESTS">
         <id name="rId" column="RID">
         </id>
-        <property name="uri" column="URI"/>
-        <property name="date" column="DATE"/>
-        <property name="issuerUid" column="ISSUERUID"/>
-        <property name="product" column="PRODUCT"/>
-        <property name="deadline" column="DEADLINE"/>
-        <property name="location" column="LOCATION"/>
-        <property name="done" column="DONE"/>
+        <property name="uri" column="URI" not-null="true"/>
+        <property name="date" column="DATE" not-null="true"/>
+        <property name="issuerUid" column="ISSUERUID" not-null="true"/>
+        <property name="product" column="PRODUCT" not-null="true"/>
+        <property name="deadline" column="DEADLINE" not-null="true"/>
+        <property name="location" column="LOCATION" not-null="true"/>
+        <property name="done" column="DONE" not-null="true"/>
     </class>
 
 </hibernate-mapping>
diff --git a/src/main/resources/Token.hbm.xml b/src/main/resources/Token.hbm.xml
index 72bf3d8..0f374d5 100644
--- a/src/main/resources/Token.hbm.xml
+++ b/src/main/resources/Token.hbm.xml
@@ -15,7 +15,7 @@
     <class name="Token" table="TOKEN">
         <id name="token" column="TOKEN">
         </id>
-        <property name="uId" column="UID"/>
+        <property name="uId" column="UID" not-null="true"/>
     </class>
 
 </hibernate-mapping>
\ No newline at end of file
diff --git a/src/main/resources/User.hbm.xml b/src/main/resources/User.hbm.xml
index edf996c..de6de5f 100644
--- a/src/main/resources/User.hbm.xml
+++ b/src/main/resources/User.hbm.xml
@@ -15,10 +15,10 @@
     <class name="User" table="USER">
         <id name="uId" column="UID">
         </id>
-        <property name="name" column="NAME"/>
-        <property name="uri" column="URI"/>
-        <property name="iconUri" column="ICONURI"/>
-        <property name="login" column="LOGIN"/>
+        <property name="name" column="NAME" not-null="true"/>
+        <property name="uri" column="URI" not-null="true"/>
+        <property name="iconUri" column="ICONURI" not-null="false"/>
+        <property name="login" column="LOGIN" not-null="true"/>
         <set name = "groups"
              table = "GROUP_MEMBER"
              lazy = "true"