diff --git a/src/zutil/db/bean/DBBean.java b/src/zutil/db/bean/DBBean.java
index 8775600..070fb89 100755
--- a/src/zutil/db/bean/DBBean.java
+++ b/src/zutil/db/bean/DBBean.java
@@ -267,7 +267,7 @@ public abstract class DBBean {
                                     sql = "UPDATE " + linkTable + " SET " + idCol + "=? WHERE " + subIdCol + "=?";
                                 else
                                     sql = "INSERT INTO " + linkTable + " (" + idCol + ", " + subIdCol + ") SELECT ?,? " +
-                                            "WHERE NOT EXISTS(SELECT 1 FROM " + linkTable + " WHERE " + idCol + "=? AND " + idCol + "=?);";
+                                            "WHERE NOT EXISTS(SELECT 1 FROM " + linkTable + " WHERE " + idCol + "=? AND " + subIdCol + "=?);";
                                 logger.finest("Save sub Bean(" + c.getName() + ", id: " + subObj.getId() + ") query: " + sql);
                                 PreparedStatement subStmt = db.getPreparedStatement(sql);
                                 subStmt.setLong(1, this.id);
diff --git a/test/zutil/db/bean/DBBeanLoadTest.java b/test/zutil/db/bean/DBBeanLoadTest.java
index c13e641..c4b4c83 100755
--- a/test/zutil/db/bean/DBBeanLoadTest.java
+++ b/test/zutil/db/bean/DBBeanLoadTest.java
@@ -51,4 +51,111 @@ public class DBBeanLoadTest {
 
         assertSame(obj1, obj2);
     }
+
+    ////////////////////////////////////////////////////////////////////////////////////////////
+    ////////////////////////////////////////////////////////////////////////////////////////////
+
+    @Test
+    public void aliasFieldsLoad() throws SQLException {
+        aliasFieldsInit(db);
+        insert(db, "aliasTable", "5", "1234", "\"helloworld\"");
+        AliasFieldsTestClass obj = DBBean.load(db, AliasFieldsTestClass.class, 5);
+
+        assertEquals((Long)5L, obj.getId());
+        assertEquals(1234, obj.intField);
+        assertEquals("helloworld", obj.strField);
+    }
+
+    ////////////////////////////////////////////////////////////////////////////////////////////
+    ////////////////////////////////////////////////////////////////////////////////////////////
+
+    @Test
+    public void emptySubObjectLoad() throws SQLException {
+        subObjectInit(db);
+        insert(db, "parent", "5");
+        ParentTestClass obj = DBBean.load(db, ParentTestClass.class, 5);
+
+        assertEquals((Long)5L, obj.getId());
+        assertEquals(0, obj.subobjs.size());
+    }
+
+    @Test
+    public void subObjectLoad() throws SQLException {
+        subObjectInit(db);
+        insert(db, "parent", "5");
+        insert(db, "subobject", "10", "5", "1234");
+        ParentTestClass obj = DBBean.load(db, ParentTestClass.class, 5);
+
+        assertEquals(1, obj.subobjs.size());
+        assertEquals((Long)10L, obj.subobjs.get(0).getId());
+        assertEquals(1234, obj.subobjs.get(0).intField);
+    }
+
+    @Test
+    public void multiSubObjectLoad() throws SQLException {
+        subObjectInit(db);
+        insert(db, "parent", "5");
+        insert(db, "subobject", "10", "5", "1001");
+        insert(db, "subobject", "11", "5", "1002");
+        insert(db, "subobject", "12", "5", "1003");
+        insert(db, "subobject", "13", "5", "1004");
+        ParentTestClass obj = DBBean.load(db, ParentTestClass.class, 5);
+
+        assertEquals(4, obj.subobjs.size());
+        assertEquals((Long)10L, obj.subobjs.get(0).getId());
+        assertEquals(1001, obj.subobjs.get(0).intField);
+        assertEquals((Long)11L, obj.subobjs.get(1).getId());
+        assertEquals(1002, obj.subobjs.get(1).intField);
+        assertEquals((Long)12L, obj.subobjs.get(2).getId());
+        assertEquals(1003, obj.subobjs.get(2).intField);
+        assertEquals((Long)13L, obj.subobjs.get(3).getId());
+        assertEquals(1004, obj.subobjs.get(3).intField);
+    }
+
+    ////////////////////////////////////////////////////////////////////////////////////////////
+    ////////////////////////////////////////////////////////////////////////////////////////////
+
+    @Test
+    public void emptySubLinkObjectLoad() throws SQLException {
+        subLinkObjectInit(db);
+        insert(db, "parent", "5");
+        ParentLinkTestClass obj = DBBean.load(db, ParentLinkTestClass.class, 5);
+
+        assertEquals((Long)5L, obj.getId());
+        assertEquals(0, obj.subobjs.size());
+    }
+
+    @Test
+    public void subLinkObjectLoad() throws SQLException {
+        subLinkObjectInit(db);
+        insert(db, "parent", "5");
+        insert(db, "link", "5", "10");
+        insert(db, "subobject", "10", "1234");
+        ParentLinkTestClass obj = DBBean.load(db, ParentLinkTestClass.class, 5);
+
+        assertEquals(1, obj.subobjs.size());
+        assertEquals((Long)10L, obj.subobjs.get(0).getId());
+        assertEquals(1234, obj.subobjs.get(0).intField);
+    }
+
+    @Test
+    public void multiSubLinkObjectLoad() throws SQLException {
+        subLinkObjectInit(db);
+        insert(db, "parent", "5");
+        insert(db, "link", "5", "10");
+        insert(db, "link", "5", "11");
+        insert(db, "link", "5", "12");
+        insert(db, "subobject", "10", "1001");
+        insert(db, "subobject", "11", "1002");
+        insert(db, "subobject", "12", "1003");
+        ParentLinkTestClass obj = DBBean.load(db, ParentLinkTestClass.class, 5);
+
+        assertEquals(3, obj.subobjs.size());
+        assertEquals((Long)10L, obj.subobjs.get(0).getId());
+        assertEquals(1001, obj.subobjs.get(0).intField);
+        assertEquals((Long)11L, obj.subobjs.get(1).getId());
+        assertEquals(1002, obj.subobjs.get(1).intField);
+        assertEquals((Long)12L, obj.subobjs.get(2).getId());
+        assertEquals(1003, obj.subobjs.get(2).intField);
+    }
 }
\ No newline at end of file
diff --git a/test/zutil/db/bean/DBBeanSaveTest.java b/test/zutil/db/bean/DBBeanSaveTest.java
index 24cb01b..27b2b68 100755
--- a/test/zutil/db/bean/DBBeanSaveTest.java
+++ b/test/zutil/db/bean/DBBeanSaveTest.java
@@ -86,6 +86,21 @@ public class DBBeanSaveTest {
     ////////////////////////////////////////////////////////////////////////////////////////////
     ////////////////////////////////////////////////////////////////////////////////////////////
 
+    @Test
+    public void emptySubObjectCreate() throws SQLException {
+        subObjectInit(db);
+        ParentTestClass obj = new ParentTestClass();
+        obj.subobjs = null;
+        obj.save(db);
+
+        assertEquals(0, getRowCount(db, "subobject"));
+
+        obj = new ParentTestClass();
+        obj.save(db);
+
+        assertEquals(0, getRowCount(db, "subobject"));
+    }
+
     @Test
     public void subObjectCreate() throws SQLException {
         ParentTestClass obj = subObjectInit(db);
@@ -111,6 +126,45 @@ public class DBBeanSaveTest {
                 getColumnValue(db, "subobject", "parent_id"));
     }
 
+    @Test
+    public void multiSubObjectCreate() throws SQLException {
+        ParentTestClass obj = subObjectInit(db);
+        obj.subobjs.add(new SubObjectTestClass());
+        obj.subobjs.add(new SubObjectTestClass());
+        obj.subobjs.get(0).intField = 1001;
+        obj.subobjs.get(1).intField = 1002;
+        obj.subobjs.get(2).intField = 1003;
+        obj.save(db);
+
+        assertEquals(3, getRowCount(db, "subobject"));
+        assertEquals(1, getColumnValue(db, "subobject", "1", "parent_id"));
+        assertEquals(1001, getColumnValue(db, "subobject", "1", "intField"));
+        assertEquals(1, getColumnValue(db, "subobject", "2", "parent_id"));
+        assertEquals(1002, getColumnValue(db, "subobject", "2", "intField"));
+        assertEquals(1, getColumnValue(db, "subobject", "3", "parent_id"));
+        assertEquals(1003, getColumnValue(db, "subobject", "3", "intField"));
+    }
+
+    @Test
+    public void multiSubObjectUpdate() throws SQLException {
+        ParentTestClass obj = subObjectInit(db);
+        obj.subobjs.add(new SubObjectTestClass());
+        obj.subobjs.add(new SubObjectTestClass());
+        obj.save(db);
+        obj.subobjs.get(0).intField = 1001;
+        obj.subobjs.get(1).intField = 1002;
+        obj.subobjs.get(2).intField = 1003;
+        obj.save(db);
+
+        assertEquals(3, getRowCount(db, "subobject"));
+        assertEquals(1, getColumnValue(db, "subobject", "1", "parent_id"));
+        assertEquals(1001, getColumnValue(db, "subobject", "1", "intField"));
+        assertEquals(1, getColumnValue(db, "subobject", "2", "parent_id"));
+        assertEquals(1002, getColumnValue(db, "subobject", "2", "intField"));
+        assertEquals(1, getColumnValue(db, "subobject", "3", "parent_id"));
+        assertEquals(1003, getColumnValue(db, "subobject", "3", "intField"));
+    }
+
     ////////////////////////////////////////////////////////////////////////////////////////////
     ////////////////////////////////////////////////////////////////////////////////////////////
 
@@ -144,4 +198,44 @@ public class DBBeanSaveTest {
                 getColumnValue(db, "subobject", "intField"));
     }
 
+    @Test
+    public void multiSubLinkObjectCreate() throws SQLException {
+        ParentLinkTestClass obj = subLinkObjectInit(db);
+        obj.subobjs.add(new SubObjectTestClass());
+        obj.subobjs.add(new SubObjectTestClass());
+        obj.subobjs.get(0).intField = 1001;
+        obj.subobjs.get(1).intField = 1002;
+        obj.subobjs.get(2).intField = 1003;
+        obj.save(db);
+
+        assertEquals(3, getRowCount(db, "link"));
+        assertEquals(1, getColumnValue(db, "link", "1", "parent_id"));
+        assertEquals(1, getColumnValue(db, "link", "2", "parent_id"));
+        assertEquals(1, getColumnValue(db, "link", "3", "parent_id"));
+        assertEquals(3, getRowCount(db, "subobject"));
+        assertEquals(1001, getColumnValue(db, "subobject", "1", "intField"));
+        assertEquals(1002, getColumnValue(db, "subobject", "2", "intField"));
+        assertEquals(1003, getColumnValue(db, "subobject", "3", "intField"));
+    }
+
+    @Test
+    public void multiSubLinkObjectUpdate() throws SQLException {
+        ParentLinkTestClass obj = subLinkObjectInit(db);
+        obj.subobjs.add(new SubObjectTestClass());
+        obj.subobjs.add(new SubObjectTestClass());
+        obj.save(db);
+        obj.subobjs.get(0).intField = 1001;
+        obj.subobjs.get(1).intField = 1002;
+        obj.subobjs.get(2).intField = 1003;
+        obj.save(db);
+
+        assertEquals(3, getRowCount(db, "link"));
+        assertEquals(1, getColumnValue(db, "link", "1", "parent_id"));
+        assertEquals(1, getColumnValue(db, "link", "2", "parent_id"));
+        assertEquals(1, getColumnValue(db, "link", "3", "parent_id"));
+        assertEquals(3, getRowCount(db, "subobject"));
+        assertEquals(1001, getColumnValue(db, "subobject", "1", "intField"));
+        assertEquals(1002, getColumnValue(db, "subobject", "2", "intField"));
+        assertEquals(1003, getColumnValue(db, "subobject", "3", "intField"));
+    }
 }
\ No newline at end of file
diff --git a/test/zutil/db/bean/DBBeanTestBase.java b/test/zutil/db/bean/DBBeanTestBase.java
index 68e558d..920543d 100755
--- a/test/zutil/db/bean/DBBeanTestBase.java
+++ b/test/zutil/db/bean/DBBeanTestBase.java
@@ -2,17 +2,20 @@ package zutil.db.bean;
 
 import zutil.StringUtil;
 import zutil.db.DBConnection;
+import zutil.db.SQLResultHandler;
 import zutil.db.handler.SimpleSQLResult;
+import zutil.log.LogUtil;
 
 import java.sql.SQLException;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.List;
+import java.util.logging.Logger;
 
 /**
  *
  */
 public class DBBeanTestBase {
+    private static final Logger logger = LogUtil.getLogger();
 
 
     public static class SimpleTestClass extends DBBean{
@@ -21,7 +24,7 @@ public class DBBeanTestBase {
     }
 
     public static SimpleTestClass simpleClassInit(DBConnection db) throws SQLException {
-        db.exec("CREATE TABLE SimpleTestClass (" +
+        execSql(db,"CREATE TABLE SimpleTestClass (" +
                 "id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, " +
                 "intField INTEGER, " +
                 "strField TEXT);");
@@ -44,7 +47,7 @@ public class DBBeanTestBase {
     }
 
     public static AliasFieldsTestClass aliasFieldsInit(DBConnection db) throws SQLException {
-        db.exec("CREATE TABLE aliasTable (" +
+        execSql(db,"CREATE TABLE aliasTable (" +
                 "id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, " +
                 "aliasIntField INTEGER, " +
                 "aliasStrField TEXT);");
@@ -69,9 +72,9 @@ public class DBBeanTestBase {
     }
 
     public static ParentTestClass subObjectInit(DBConnection db) throws SQLException {
-        db.exec("CREATE TABLE parent (" +
+        execSql(db,"CREATE TABLE parent (" +
                 "id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT);");
-        db.exec("CREATE TABLE subobject (" +
+        execSql(db,"CREATE TABLE subobject (" +
                 "id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, " +
                 "parent_id INTEGER, " +
                 "intField INTEGER);");
@@ -93,14 +96,13 @@ public class DBBeanTestBase {
     }
 
     public static ParentLinkTestClass subLinkObjectInit(DBConnection db) throws SQLException {
-        db.exec("CREATE TABLE parent (" +
+        execSql(db,"CREATE TABLE parent (" +
                 "id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT);");
-        db.exec("CREATE TABLE link (" +
+        execSql(db,"CREATE TABLE link (" +
                 "parent_id INTEGER, " +
                 "id INTEGER);");
-        db.exec("CREATE TABLE subobject (" +
+        execSql(db,"CREATE TABLE subobject (" +
                 "id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, " +
-                "parent_id INTEGER, " +
                 "intField INTEGER);");
 
         ParentLinkTestClass obj = new ParentLinkTestClass();
@@ -114,15 +116,27 @@ public class DBBeanTestBase {
     ////////////////////////////////////////////////////////////////////////////////////////////
 
     public static Object getColumnValue(DBConnection db, String table, String column) throws SQLException {
-        return db.exec("SELECT "+column+" FROM "+table, new SimpleSQLResult<>());
+        return execSql(db, "SELECT "+column+" FROM "+table, new SimpleSQLResult<>());
+    }
+    public static Object getColumnValue(DBConnection db, String table, String id, String column) throws SQLException {
+        return execSql(db, "SELECT "+column+" FROM "+table+" WHERE id="+id, new SimpleSQLResult<>());
     }
 
     public static Object getRowCount(DBConnection db, String table) throws SQLException {
-        return db.exec("SELECT count(*) FROM "+table, new SimpleSQLResult<>());
+        return execSql(db, "SELECT count(*) FROM "+table, new SimpleSQLResult<>());
     }
 
     public static void insert(DBConnection db, String table, String... values) throws SQLException {
-        db.exec("INSERT INTO "+table+" VALUES("+
-                StringUtil.join(",", values)+");");
+        execSql(db, "INSERT INTO "+table+" VALUES("+StringUtil.join(",", values)+");");
+    }
+
+    private static void execSql(DBConnection db, String sql) throws SQLException {
+        logger.info("SQL: "+sql);
+        db.exec(sql);
+    }
+
+    private static Object execSql(DBConnection db, String sql, SQLResultHandler handler) throws SQLException {
+        logger.info("SQL RET: "+sql);
+        return db.exec(sql, handler);
     }
 }
\ No newline at end of file