diff --git a/src/main/java/cn/devezhao/persist4j/Record.java b/src/main/java/cn/devezhao/persist4j/Record.java
index 47d9f9e..5d0f2f4 100644
--- a/src/main/java/cn/devezhao/persist4j/Record.java
+++ b/src/main/java/cn/devezhao/persist4j/Record.java
@@ -8,6 +8,7 @@
 import java.util.Iterator;
 
 import cn.devezhao.persist4j.engine.ID;
+import cn.devezhao.persist4j.engine.NullValue;
 
 /**
  * 记录
@@ -18,73 +19,236 @@
  */
 public interface Record extends Cloneable, Serializable {
 
+	/**
+	 * 实体
+	 * 
+	 * @return
+	 */
 	Entity getEntity();
 
+	/**
+	 * 编辑用户
+	 * 
+	 * @return
+	 */
 	ID getEditor();
 
+	/**
+	 * 主键
+	 * 
+	 * @return
+	 */
 	ID getPrimary();
 
+	/**
+	 * @param key
+	 * @param value
+	 * @return
+	 */
 	Record setID(String key, ID value);
 
+	/**
+	 * @param key
+	 * @return
+	 */
 	ID getID(String key);
 
+	/**
+	 * @param key
+	 * @param values
+	 * @return
+	 */
 	Record setIDArray(String key, ID[] values);
 
+	/**
+	 * @param key
+	 * @return
+	 */
 	ID[] getIDArray(String key);
 
+	/**
+	 * @param key
+	 * @param value
+	 * @return
+	 */
 	Record setChar(String key, Character value);
 
+	/**
+	 * @param key
+	 * @return
+	 */
 	Character getChar(String key);
 
+	/**
+	 * @param key
+	 * @param value
+	 * @return
+	 */
 	Record setString(String key, String value);
 
+	/**
+	 * @param key
+	 * @return
+	 */
 	String getString(String key);
 
+	/**
+	 * @param key
+	 * @param value
+	 * @return
+	 */
 	Record setInt(String key, Integer value);
 
+	/**
+	 * @param key
+	 * @return
+	 */
 	Integer getInt(String key);
 
+	/**
+	 * @param key
+	 * @param value
+	 * @return
+	 */
 	Record setDouble(String key, Double value);
 
+	/**
+	 * @param key
+	 * @return
+	 */
 	Double getDouble(String key);
 
+	/**
+	 * @param key
+	 * @param value
+	 * @return
+	 */
 	Record setDecimal(String key, BigDecimal value);
 
+	/**
+	 * @param key
+	 * @return
+	 */
 	BigDecimal getDecimal(String key);
 	
+	/**
+	 * @param key
+	 * @param value
+	 * @return
+	 */
 	Record setLong(String key, Long value);
 	
+	/**
+	 * @param key
+	 * @return
+	 */
 	Long getLong(String key);
 
+	/**
+	 * @param key
+	 * @param value
+	 * @return
+	 */
 	Record setDate(String key, Date value);
 
+	/**
+	 * @param key
+	 * @return
+	 */
 	Date getDate(String key);
 
+	/**
+	 * @param key
+	 * @param value
+	 * @return
+	 */
 	Record setBoolean(String key, Boolean value);
 
+	/**
+	 * @param key
+	 * @return
+	 */
 	Boolean getBoolean(String key);
 
+	/**
+	 * @param key
+	 * @param stream
+	 * @return
+	 */
 	Record setBinary(String key, InputStream stream);
 
+	/**
+	 * @param key
+	 * @return
+	 */
 	InputStream getBinary(String key);
 
+	/**
+	 * @param key
+	 * @param value
+	 * @return
+	 */
 	Record setReader(String key, Reader value);
 
+	/**
+	 * @param key
+	 * @param value
+	 * @return
+	 */
 	Record setReader(String key, String value);
 
+	/**
+	 * @param key
+	 * @return
+	 */
 	Reader getReader(String key);
 
+	/**
+	 * @param key
+	 * @param value
+	 * @return
+	 */
 	Record setObjectValue(String key, Object value);
 
+	/**
+	 * @param key
+	 * @return
+	 */
 	Object getObjectValue(String key);
 
+	/**
+	 * @param key
+	 * @return
+	 */
 	boolean hasValue(String key);
 	
+	/**
+	 * @param key
+	 * @param includeNullValue {@link NullValue}
+	 * @return
+	 * @see #setNull(String)
+	 */
+	boolean hasValue(String key, boolean includeNullValue);
+	
+	/**
+	 * @param key
+	 * @return
+	 */
 	Object removeValue(String key);
 	
+	/**
+	 * @param key
+	 * @return
+	 */
 	Object setNull(String key);
 
+	/**
+	 * @return
+	 */
 	Iterator<String> getAvailableFieldIterator();
 
+	/**
+	 * @return
+	 */
 	Record clone();
 }
diff --git a/src/main/java/cn/devezhao/persist4j/engine/StandardRecord.java b/src/main/java/cn/devezhao/persist4j/engine/StandardRecord.java
index f2fc1e4..c2f0ac2 100644
--- a/src/main/java/cn/devezhao/persist4j/engine/StandardRecord.java
+++ b/src/main/java/cn/devezhao/persist4j/engine/StandardRecord.java
@@ -48,7 +48,7 @@ public class StandardRecord implements Record {
 	protected Map<String, Object> recordMap = new CaseInsensitiveMap<>();
 
 	/**
-	 * Serializable
+	 * for Serializable
 	 */
 	protected StandardRecord() {
 		this.entity = null;
@@ -56,8 +56,6 @@ protected StandardRecord() {
 	}
 	
 	/**
-	 * Create a new StandardRecordImpl
-	 * 
 	 * @param entity
 	 */
 	public StandardRecord(Entity entity) {
@@ -65,43 +63,47 @@ public StandardRecord(Entity entity) {
 	}
 	
 	/**
-	 * Create a new StandardRecordImpl
-	 * 
 	 * @param entity
 	 * @param editor
 	 */
 	public StandardRecord(Entity entity, ID editor) {
-		Validate.notNull(entity, "entity must not be null");
+		Validate.notNull(entity, "'entity' must not be null");
 		this.entity = entity;
 		this.editor = editor;
 	}
-
+	
+	@Override
 	public Entity getEntity() {
 		return entity;
 	}
-
+	
+	@Override
 	public ID getEditor() {
 		return editor;
 	}
-
+	
+	@Override
 	public ID getPrimary() {
 		return getID(entity.getPrimaryField().getName());
 	}
-
+	
+	@Override
 	public ID getID(String key) {
 		return (ID) getObject(key, ID.class);
 	}
-
+	
+	@Override
 	public Record setID(String key, ID value) {
 		if (entity.getPrimaryField().getName().equalsIgnoreCase(key) && getPrimary() != null) {
 			throw new IllegalStateException(
-					"primary field value already exists, can not be re-settings");
+					"Primary field value already exists, can not be re-settings");
 		}
 		
 		setObject(key, value);
 		return this;
 	}
-
+	
+	@Override
 	public ID[] getIDArray(String key) {
 		Object v = recordMap.get(key);
 		if (v == null) {
@@ -109,91 +111,111 @@ public ID[] getIDArray(String key) {
 		}
 		return (ID[]) v;
 	}
-
+	
+	@Override
 	public Record setIDArray(String key, ID[] value) {
 		setObject(key, value);
 		return this;
 	}
-
+	
+	@Override
 	public Character getChar(String key) {
 		return (Character) getObject(key, Character.class);
 	}
-
+	
+	@Override
 	public Record setChar(String key, Character value) {
 		setObject(key, value);
 		return this;
 	}
-
+	
+	@Override
 	public String getString(String key) {
 		return (String) getObject(key, String.class);
 	}
-
+	
+	@Override
 	public Record setString(String key, String value) {
 		setObject(key, value);
 		return this;
 	}
-
+	
+	@Override
 	public Integer getInt(String key) {
 		return (Integer) getObject(key, Integer.class);
 	}
-
+	
+	@Override
 	public Record setInt(String key, Integer value) {
 		setObject(key, value);
 		return this;
 	}
-
+	
+	@Override
 	public Double getDouble(String key) {
 		return (Double) getObject(key, Double.class);
 	}
-
+	
+	@Override
 	public Record setDouble(String key, Double value) {
 		setObject(key, value);
 		return this;
 	}
-
+	
+	@Override
 	public BigDecimal getDecimal(String key) {
 		return (BigDecimal) getObject(key, BigDecimal.class);
 	}
-
+	
+	@Override
 	public Record setDecimal(String key, BigDecimal value) {
 		setObject(key, value);
 		return this;
 	}
 	
+	@Override
 	public Long getLong(String key) {
 		return (Long) getObject(key, Long.class);
 	}
 	
+	@Override
 	public Record setLong(String key, Long value) {
 		setObject(key, value);
 		return this;
 	}
 
+	@Override
 	public Date getDate(String key) {
 		return (Date) getObject(key, Date.class);
 	}
 
+	@Override
 	public Record setDate(String key, Date value) {
 		setObject(key, value);
 		return this;
 	}
 
+	@Override
 	public Boolean getBoolean(String key) {
 		return (Boolean) getObject(key, Boolean.class);
 	}
 
+	@Override
 	public Record setBoolean(String key, Boolean value) {
 		setObject(key, value);
 		return this;
 	}
 
+	@Override
 	public Reader getReader(String key) {
 		return null;
 	}
 
+	@Override
 	public Record setReader(String key, Reader value) {
-		if (value == null)
+		if (value == null) {
 			return this;
+		}
 		
 		String content = null;
 		try {
@@ -204,6 +226,7 @@ public Record setReader(String key, Reader value) {
 		return setReader(key, content);
 	}
 
+	@Override
 	public Record setReader(String key, String value) {
 		if (value == null) {
 			return this;
@@ -212,52 +235,63 @@ public Record setReader(String key, String value) {
 		return this;
 	}
 
+	@Override
 	public InputStream getBinary(String key) {
 		throw new UnsupportedOperationException();
 	}
 
+	@Override
 	public Record setBinary(String key, InputStream value) {
 		setObject(key, value);
 		return this;
 	}
 
-	public Record getRecord(String key) {
-		throw new UnsupportedOperationException();
-	}
-
-	public Record setRecord(String key, Record value) {
-		throw new UnsupportedOperationException();
-	}
-
+	@Override
 	public Object getObjectValue(String key) {
 		return recordMap.get(key);
 	}
 
+	@Override
 	public Record setObjectValue(String key, Object value) {
-		if (key == null || value == null)
+		if (key == null || value == null) {
 			return this;
+		}
 		recordMap.put(key, value);
 		return this;
 	}
 
+	@Override
 	public boolean hasValue(String key) {
-		return recordMap.containsKey(key);
+		return hasValue(key, true);
+	}
+	
+	@Override
+	public boolean hasValue(String key, boolean includeNullValue) {
+		boolean has = recordMap.containsKey(key);
+		if (!has) {
+			return false;
+		}
+		return includeNullValue ? true : !NullValue.is(recordMap.get(key));
 	}
 	
+	@Override
 	public Object removeValue(String key) {
 		return recordMap.remove(key);
 	}
 	
+	@Override
 	public Object setNull(String key) {
 		Object old = recordMap.get(key);
 		recordMap.put(key, new NullValue());
 		return old;
 	}
 
+	@Override
 	public Iterator<String> getAvailableFieldIterator() {
 		return recordMap.keySet().iterator();
 	}
 
+	@Override
 	public Record clone() {
 		StandardRecord o = null;
 		try {
@@ -287,7 +321,7 @@ protected void setObject(String key, Object value) {
 
 		if (LOG.isDebugEnabled()) {
 			if (recordMap.containsKey(key)) {
-				LOG.warn("update field [" + key + "] value. OLD: " + recordMap.get(key) + ", NEW: " + value);
+				LOG.warn("Update field [" + key + "] value. OLD: " + recordMap.get(key) + ", NEW: " + value);
 			}
 		}
 		recordMap.put(key, value);
@@ -307,7 +341,7 @@ protected Object getObject(String key, Class<?> clazz) {
 		}
 		
 		throw new PersistException(
-				"can't cast field [ " + key + " ] value type " + v.getClass() + " to " + clazz);
+				"Can't cast field [ " + key + " ] value type " + v.getClass() + " to " + clazz);
 	}
 	
 	protected void checkReferenceValue(Field field, Object value) {