improved SchemaStatVisitor, support function condition

src/main/java/com/alibaba/druid/sql/visitor/SchemaStatVisitor.java

@@ -383,6 +383,7 @@ public class SchemaStatVisitor extends SQLASTVisitorAdapter {
             case GreaterThan:
             case GreaterThanOrEqual:
             case LessThan:
+            case LessThanOrGreater:
             case LessThanOrEqual:
             case LessThanOrEqualOrGreaterThan:
             case Like:
@@ -459,6 +460,14 @@ public class SchemaStatVisitor extends SQLASTVisitorAdapter {
         if (aliasMap == null) {
             return null;
         }
+        
+        if (expr instanceof SQLMethodInvokeExpr) {
+            SQLMethodInvokeExpr methodInvokeExp = (SQLMethodInvokeExpr) expr;
+            if (methodInvokeExp.getParameters().size() == 1) {
+                SQLExpr firstExpr = methodInvokeExp.getParameters().get(0);
+                return getColumn(firstExpr);
+            }
+        }
 
         if (expr instanceof SQLPropertyExpr) {
             SQLExpr owner = ((SQLPropertyExpr) expr).getOwner();

src/main/java/com/alibaba/druid/support/json/JSONWriter.java

@@ -15,6 +15,7 @@
  */
 package com.alibaba.druid.support.json;
 
+import com.alibaba.druid.sql.visitor.SQLEvalVisitor;
 import com.alibaba.druid.util.Utils;
 
 import javax.management.openmbean.CompositeData;
@@ -127,6 +128,11 @@ public class JSONWriter {
             writeMap((Map) o);
             return;
         }
+        
+        if (o == SQLEvalVisitor.EVAL_VALUE_NULL) {
+            write("null");
+            return;
+        }
 
         throw new IllegalArgumentException("not support type : " + o.getClass());
     }

src/main/java/com/alibaba/druid/support/opds/udf/ExportConditions.java

@@ -22,6 +22,7 @@ import com.alibaba.druid.sql.SQLUtils;
 import com.alibaba.druid.sql.ast.SQLStatement;
 import com.alibaba.druid.sql.visitor.SchemaStatVisitor;
 import com.alibaba.druid.stat.TableStat;
+import com.alibaba.druid.stat.TableStat.Column;
 import com.alibaba.druid.stat.TableStat.Condition;
 import com.alibaba.druid.support.json.JSONUtils;
 import com.aliyun.odps.udf.UDF;
@@ -45,12 +46,13 @@ public class ExportConditions extends UDF {
             List<Condition> conditions = visitor.getConditions();
             for (int i = 0; i < conditions.size(); ++i) {
                 TableStat.Condition condition = conditions.get(i);
-                String column = condition.getColumn().toString();
+                Column column = condition.getColumn();
                 String operator = condition.getOperator();
                 List<Object> values = condition.getValues();
                 
                 List<Object> row = new ArrayList<Object>();
-                row.add(column);
+                row.add(column.getTable());
+                row.add(column.getName());
                 row.add(operator);
                 if (values.size() == 0) {
                     row.add(null);