bug fixed for sql parser

src/main/java/com/alibaba/druid/sql/ast/statement/SQLColumnDefinition.java

@@ -33,10 +33,20 @@ public class SQLColumnDefinition extends SQLObjectImpl implements SQLTableElemen
     private final List<SQLColumnConstraint> constaints = new ArrayList<SQLColumnConstraint>(0);
     private String                          comment;
 
+    private Boolean                         enable;
+
     public SQLColumnDefinition(){
 
     }
 
+    public Boolean getEnable() {
+        return enable;
+    }
+
+    public void setEnable(Boolean enable) {
+        this.enable = enable;
+    }
+
     public SQLName getName() {
         return name;
     }

src/main/java/com/alibaba/druid/sql/ast/statement/SQLPrimaryKey.java

@@ -15,6 +15,6 @@
  */
 package com.alibaba.druid.sql.ast.statement;
 
-public interface SQLPrimaryKey extends SQLUniqueConstraint {
+public interface SQLPrimaryKey extends SQLUniqueConstraint, SQLTableElement {
 
 }

src/main/java/com/alibaba/druid/sql/ast/statement/SQLTruncateStatement.java

@@ -25,5 +25,6 @@ public class SQLTruncateStatement extends SQLStatementImpl {
         if (visitor.visit(this)) {
             acceptChild(visitor, tableNames);
         }
+        visitor.endVisit(this);
     }
 }