diff --git a/src/main/java/io/mycat/net/handler/FrontendCommandHandler.java b/src/main/java/io/mycat/net/handler/FrontendCommandHandler.java
index 79b344fc5..784e60882 100644
--- a/src/main/java/io/mycat/net/handler/FrontendCommandHandler.java
+++ b/src/main/java/io/mycat/net/handler/FrontendCommandHandler.java
@@ -28,7 +28,10 @@ import io.mycat.config.ErrorCode;
 import io.mycat.net.FrontendConnection;
 import io.mycat.net.NIOHandler;
 import io.mycat.net.mysql.MySQLPacket;
+import io.mycat.server.NonBlockingSession;
 import io.mycat.statistic.CommandCount;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -39,6 +42,7 @@ import java.util.concurrent.atomic.AtomicBoolean;
  * @author mycat
  */
 public class FrontendCommandHandler implements NIOHandler {
+    private static final Logger LOGGER = LoggerFactory.getLogger(NonBlockingSession.class);
     protected final ConcurrentLinkedQueue<byte[]> dataQueue = new ConcurrentLinkedQueue<>();
     protected final AtomicBoolean handleStatus;
     protected final FrontendConnection source;
@@ -131,6 +135,7 @@ public class FrontendCommandHandler implements NIOHandler {
                             handleData(data);
                         }
                     } catch (Exception e) {
+                        LOGGER.warn("maybe occur a bug,", e);
                         source.writeErrMessage(ErrorCode.ER_UNKNOWN_ERROR, e.toString());
                         dataQueue.clear();
                     } finally {
diff --git a/src/main/java/io/mycat/plan/common/item/Item.java b/src/main/java/io/mycat/plan/common/item/Item.java
index edb80494a..d1281f8a8 100644
--- a/src/main/java/io/mycat/plan/common/item/Item.java
+++ b/src/main/java/io/mycat/plan/common/item/Item.java
@@ -104,7 +104,7 @@ public abstract class Item {
     public ItemResult getCmpContext() {
         return cmpContext;
     }
-
+    //TODO DELETE
     public void setCmpContext(ItemResult cmpContext) {
         this.cmpContext = cmpContext;
     }
diff --git a/src/main/java/io/mycat/plan/common/item/ItemField.java b/src/main/java/io/mycat/plan/common/item/ItemField.java
index 1012e529f..14bf0771b 100644
--- a/src/main/java/io/mycat/plan/common/item/ItemField.java
+++ b/src/main/java/io/mycat/plan/common/item/ItemField.java
@@ -1,16 +1,8 @@
 package io.mycat.plan.common.item;
 
-import java.io.UnsupportedEncodingException;
-import java.math.BigDecimal;
-import java.math.BigInteger;
-import java.util.List;
-
-import org.apache.commons.lang.StringUtils;
-
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
 import com.alibaba.druid.sql.ast.expr.SQLPropertyExpr;
-
 import io.mycat.backend.mysql.CharsetUtil;
 import io.mycat.config.ErrorCode;
 import io.mycat.net.mysql.FieldPacket;
@@ -24,6 +16,12 @@ import io.mycat.plan.common.field.Field;
 import io.mycat.plan.common.time.MySQLTime;
 import io.mycat.plan.node.JoinNode;
 import io.mycat.util.StringUtil;
+import org.apache.commons.lang.StringUtils;
+
+import java.io.UnsupportedEncodingException;
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.util.List;
 
 public class ItemField extends ItemIdent {
 
@@ -75,7 +73,7 @@ public class ItemField extends ItemIdent {
 
     @Override
     public ItemResult resultType() {
-        return field.resultType();
+        return field == null ? null : field.resultType();
     }
 
     @Override
diff --git a/src/main/java/io/mycat/plan/common/item/function/operator/cmpfunc/ItemFuncIn.java b/src/main/java/io/mycat/plan/common/item/function/operator/cmpfunc/ItemFuncIn.java
index 36bdc3e3d..01f226ece 100644
--- a/src/main/java/io/mycat/plan/common/item/function/operator/cmpfunc/ItemFuncIn.java
+++ b/src/main/java/io/mycat/plan/common/item/function/operator/cmpfunc/ItemFuncIn.java
@@ -13,6 +13,7 @@ import java.util.List;
 
 
 public class ItemFuncIn extends ItemFuncOptNeg {
+    //TODO :DELETE
     private ItemResult leftResultType;
 
     /**
@@ -22,7 +23,6 @@ public class ItemFuncIn extends ItemFuncOptNeg {
      */
     public ItemFuncIn(List<Item> args, boolean isNegation) {
         super(args, isNegation);
-        leftResultType = args.get(0).resultType();
     }
 
     @Override