improved sql parser.

src/main/java/com/alibaba/druid/sql/ast/expr/SQLFlashbackExpr.java

@@ -0,0 +1,80 @@
+package com.alibaba.druid.sql.ast.expr;
+
+import com.alibaba.druid.sql.ast.SQLExpr;
+import com.alibaba.druid.sql.ast.SQLExprImpl;
+import com.alibaba.druid.sql.visitor.SQLASTVisitor;
+
+/**
+ * Created by wenshao on 14/06/2017.
+ */
+public class SQLFlashbackExpr extends SQLExprImpl {
+    private Type type;
+    private SQLExpr expr;
+
+    public SQLFlashbackExpr() {
+
+    }
+
+    public SQLFlashbackExpr(Type type, SQLExpr expr) {
+        this.type = type;
+        this.setExpr(expr);
+    }
+
+    public Type getType() {
+        return type;
+    }
+
+    public void setType(Type type) {
+        this.type = type;
+    }
+
+    public SQLExpr getExpr() {
+        return expr;
+    }
+
+    public void setExpr(SQLExpr expr) {
+        if (expr != null) {
+            expr.setParent(this);
+        }
+        this.expr = expr;
+    }
+
+    @Override
+    protected void accept0(SQLASTVisitor visitor) {
+        if (visitor.visit(this)) {
+            acceptChild(visitor, expr);
+        }
+        visitor.endVisit(this);
+    }
+
+    public SQLFlashbackExpr clone() {
+        SQLFlashbackExpr x = new SQLFlashbackExpr();
+        x.type = this.type;
+        if (expr != null) {
+            x.setExpr(expr.clone());
+        }
+        return x;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        SQLFlashbackExpr that = (SQLFlashbackExpr) o;
+
+        if (type != that.type) return false;
+        return expr != null ? expr.equals(that.expr) : that.expr == null;
+    }
+
+    @Override
+    public int hashCode() {
+        int result = type != null ? type.hashCode() : 0;
+        result = 31 * result + (expr != null ? expr.hashCode() : 0);
+        return result;
+    }
+
+    public static enum Type {
+        SCN, TIMESTAMP
+    }
+}

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

@@ -18,6 +18,7 @@ package com.alibaba.druid.sql.ast.statement;
 import java.util.ArrayList;
 import java.util.List;
 
+import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLHint;
 import com.alibaba.druid.sql.ast.SQLObjectImpl;
 
@@ -27,6 +28,8 @@ public abstract class SQLTableSourceImpl extends SQLObjectImpl implements SQLTab
 
     protected List<SQLHint> hints;
 
+    protected SQLExpr       flashback;
+
     public SQLTableSourceImpl(){
 
     }
@@ -71,4 +74,14 @@ public abstract class SQLTableSourceImpl extends SQLObjectImpl implements SQLTab
         return alias;
     }
 
+    public SQLExpr getFlashback() {
+        return flashback;
+    }
+
+    public void setFlashback(SQLExpr flashback) {
+        if (flashback != null) {
+            flashback.setParent(this);
+        }
+        this.flashback = flashback;
+    }
 }

src/main/java/com/alibaba/druid/sql/dialect/oracle/ast/clause/FlashbackQueryClause.java

@@ -1,115 +0,0 @@
-/*
- * Copyright 1999-2017 Alibaba Group Holding Ltd.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package com.alibaba.druid.sql.dialect.oracle.ast.clause;
-
-import com.alibaba.druid.sql.ast.SQLExpr;
-import com.alibaba.druid.sql.dialect.oracle.ast.OracleSQLObject;
-import com.alibaba.druid.sql.dialect.oracle.ast.OracleSQLObjectImpl;
-import com.alibaba.druid.sql.dialect.oracle.visitor.OracleASTVisitor;
-
-public abstract class FlashbackQueryClause extends OracleSQLObjectImpl {
-
-    private Type type;
-
-    public Type getType() {
-        return type;
-    }
-
-    public void setType(Type type) {
-        this.type = type;
-    }
-
-    public static enum Type {
-        SCN, TIMESTAMP
-    }
-
-    public FlashbackQueryClause clone() {
-        throw new UnsupportedOperationException();
-    }
-
-    public static class VersionsFlashbackQueryClause extends FlashbackQueryClause {
-
-        private SQLExpr begin;
-        private SQLExpr end;
-
-        public SQLExpr getBegin() {
-            return begin;
-        }
-
-        public void setBegin(SQLExpr begin) {
-            this.begin = begin;
-        }
-
-        public SQLExpr getEnd() {
-            return end;
-        }
-
-        public void setEnd(SQLExpr end) {
-            this.end = end;
-        }
-
-        @Override
-        public void accept0(OracleASTVisitor visitor) {
-            if (visitor.visit(this)) {
-                acceptChild(visitor, begin);
-                acceptChild(visitor, end);
-            }
-            visitor.endVisit(this);
-        }
-    }
-
-    public static class AsOfFlashbackQueryClause extends FlashbackQueryClause {
-
-        private SQLExpr expr;
-
-        public SQLExpr getExpr() {
-            return expr;
-        }
-
-        public void setExpr(SQLExpr expr) {
-            this.expr = expr;
-        }
-
-        @Override
-        public void accept0(OracleASTVisitor visitor) {
-            if (visitor.visit(this)) {
-                acceptChild(visitor, expr);
-            }
-            visitor.endVisit(this);
-        }
-    }
-
-    public static class AsOfSnapshotClause extends FlashbackQueryClause {
-
-        private SQLExpr expr;
-
-        public SQLExpr getExpr() {
-            return expr;
-        }
-
-        public void setExpr(SQLExpr expr) {
-            this.expr = expr;
-        }
-
-        @Override
-        public void accept0(OracleASTVisitor visitor) {
-            if (visitor.visit(this)) {
-                acceptChild(visitor, expr);
-            }
-            visitor.endVisit(this);
-        }
-    }
-}

src/main/java/com/alibaba/druid/sql/dialect/oracle/ast/stmt/OracleSelectJoin.java

@@ -18,14 +18,12 @@ package com.alibaba.druid.sql.dialect.oracle.ast.stmt;
 import com.alibaba.druid.sql.SQLUtils;
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.statement.SQLJoinTableSource;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause;
 import com.alibaba.druid.sql.dialect.oracle.visitor.OracleASTVisitor;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class OracleSelectJoin extends SQLJoinTableSource implements OracleSelectTableSource {
 
     protected OracleSelectPivotBase pivot;
-    protected FlashbackQueryClause  flashback;
 
     public OracleSelectJoin(String alias){
         super(alias);
@@ -35,13 +33,6 @@ public class OracleSelectJoin extends SQLJoinTableSource implements OracleSelect
 
     }
 
-    public FlashbackQueryClause getFlashback() {
-        return flashback;
-    }
-
-    public void setFlashback(FlashbackQueryClause flashback) {
-        this.flashback = flashback;
-    }
 
     public OracleSelectPivotBase getPivot() {
         return pivot;

src/main/java/com/alibaba/druid/sql/dialect/oracle/ast/stmt/OracleSelectSubqueryTableSource.java

@@ -16,9 +16,9 @@
 package com.alibaba.druid.sql.dialect.oracle.ast.stmt;
 
 import com.alibaba.druid.sql.SQLUtils;
+import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.statement.SQLSelect;
 import com.alibaba.druid.sql.ast.statement.SQLSubqueryTableSource;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause;
 import com.alibaba.druid.sql.dialect.oracle.visitor.OracleASTVisitor;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
@@ -26,19 +26,10 @@ public class OracleSelectSubqueryTableSource extends SQLSubqueryTableSource impl
 
     protected OracleSelectPivotBase pivot;
 
-    protected FlashbackQueryClause  flashback;
 
     public OracleSelectSubqueryTableSource(){
     }
 
-    public FlashbackQueryClause getFlashback() {
-        return flashback;
-    }
-
-    public void setFlashback(FlashbackQueryClause flashback) {
-        this.flashback = flashback;
-    }
-
     public OracleSelectSubqueryTableSource(String alias){
         super(alias);
     }

src/main/java/com/alibaba/druid/sql/dialect/oracle/ast/stmt/OracleSelectTableReference.java

@@ -17,8 +17,6 @@ package com.alibaba.druid.sql.dialect.oracle.ast.stmt;
 
 import com.alibaba.druid.sql.SQLUtils;
 import com.alibaba.druid.sql.ast.statement.SQLExprTableSource;
-import com.alibaba.druid.sql.ast.statement.SQLTableSource;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.PartitionExtensionClause;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.SampleClause;
 import com.alibaba.druid.sql.dialect.oracle.visitor.OracleASTVisitor;
@@ -32,20 +30,10 @@ public class OracleSelectTableReference extends SQLExprTableSource implements Or
     protected PartitionExtensionClause partition;
     protected SampleClause             sampleClause;
 
-    protected FlashbackQueryClause     flashback;
-
     public OracleSelectTableReference(){
 
     }
 
-    public FlashbackQueryClause getFlashback() {
-        return flashback;
-    }
-
-    public void setFlashback(FlashbackQueryClause flashback) {
-        this.flashback = flashback;
-    }
-
     public PartitionExtensionClause getPartition() {
         return partition;
     }

src/main/java/com/alibaba/druid/sql/dialect/oracle/ast/stmt/OracleSelectTableSource.java

@@ -15,8 +15,8 @@
  */
 package com.alibaba.druid.sql.dialect.oracle.ast.stmt;
 
+import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.statement.SQLTableSource;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause;
 
 public interface OracleSelectTableSource extends SQLTableSource {
 
@@ -24,7 +24,7 @@ public interface OracleSelectTableSource extends SQLTableSource {
 
     void setPivot(OracleSelectPivotBase pivot);
 
-    FlashbackQueryClause getFlashback();
+    SQLExpr getFlashback();
 
-    void setFlashback(FlashbackQueryClause flashback);
+    void setFlashback(SQLExpr flashback);
 }

src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleSelectParser.java

@@ -20,17 +20,9 @@ import java.util.List;
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLOrderBy;
 import com.alibaba.druid.sql.ast.SQLSetQuantifier;
-import com.alibaba.druid.sql.ast.expr.SQLAggregateExpr;
-import com.alibaba.druid.sql.ast.expr.SQLBinaryOpExpr;
-import com.alibaba.druid.sql.ast.expr.SQLBinaryOperator;
-import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
-import com.alibaba.druid.sql.ast.expr.SQLListExpr;
+import com.alibaba.druid.sql.ast.expr.*;
 import com.alibaba.druid.sql.ast.statement.*;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.CycleClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause.AsOfFlashbackQueryClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause.AsOfSnapshotClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause.VersionsFlashbackQueryClause;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.ModelClause;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.ModelClause.CellAssignment;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.ModelClause.CellAssignmentItem;
@@ -695,61 +687,47 @@ public class OracleSelectParser extends SQLSelectParser {
         }
 
         if (identifierEquals("VERSIONS")) {
+            SQLBetweenExpr betweenExpr = new SQLBetweenExpr();
+            betweenExpr.setTestExpr(new SQLIdentifierExpr("VERSIONS"));
             lexer.nextToken();
 
-            if (lexer.token() == Token.BETWEEN) {
+            accept(Token.BETWEEN);
+
+
+            SQLFlashbackExpr start = new SQLFlashbackExpr();
+            if (identifierEquals("SCN")) {
                 lexer.nextToken();
-
-                VersionsFlashbackQueryClause clause = new VersionsFlashbackQueryClause();
-                if (identifierEquals("SCN")) {
-                    clause.setType(AsOfFlashbackQueryClause.Type.SCN);
-                    lexer.nextToken();
-                } else {
-                    acceptIdentifier("TIMESTAMP");
-                    clause.setType(AsOfFlashbackQueryClause.Type.TIMESTAMP);
-                }
-
-                SQLBinaryOpExpr binaryExpr = (SQLBinaryOpExpr) exprParser.expr();
-                if (binaryExpr.getOperator() != SQLBinaryOperator.BooleanAnd) {
-                    throw new ParserException("syntax error : " + binaryExpr.getOperator());
-                }
-
-                clause.setBegin(binaryExpr.getLeft());
-                clause.setEnd(binaryExpr.getRight());
-
-                tableReference.setFlashback(clause);
+                start.setType(SQLFlashbackExpr.Type.SCN);
             } else {
-                throw new ParserException("TODO");
+                acceptIdentifier("TIMESTAMP");
+                start.setType(SQLFlashbackExpr.Type.TIMESTAMP);
             }
+
+            SQLBinaryOpExpr binaryExpr = (SQLBinaryOpExpr) exprParser.expr();
+            if (binaryExpr.getOperator() != SQLBinaryOperator.BooleanAnd) {
+                throw new ParserException("syntax error : " + binaryExpr.getOperator());
+            }
+
+            start.setExpr(binaryExpr.getLeft());
+
+            betweenExpr.setBeginExpr(start);
+            betweenExpr.setEndExpr(binaryExpr.getRight());
+
+            tableReference.setFlashback(betweenExpr);
         }
 
     }
 
-    private FlashbackQueryClause flashback() {
+    private SQLExpr flashback() {
         accept(Token.OF);
-
         if (identifierEquals("SCN")) {
-            AsOfFlashbackQueryClause clause = new AsOfFlashbackQueryClause();
-            clause.setType(AsOfFlashbackQueryClause.Type.SCN);
             lexer.nextToken();
-            clause.setExpr(exprParser.expr());
-
-            return clause;
+            return new SQLFlashbackExpr(SQLFlashbackExpr.Type.SCN, this.expr());
         } else if (identifierEquals("SNAPSHOT")) {
-            lexer.nextToken();
-            accept(Token.LPAREN);
-            AsOfSnapshotClause clause = new AsOfSnapshotClause();
-            clause.setExpr(this.expr());
-            accept(Token.RPAREN);
-
-            return clause;
+            return this.expr();
         } else {
-            AsOfFlashbackQueryClause clause = new AsOfFlashbackQueryClause();
-            acceptIdentifier("TIMESTAMP");
-            clause.setType(AsOfFlashbackQueryClause.Type.TIMESTAMP);
-            clause.setExpr(exprParser.expr());
-
-            return clause;
+            lexer.nextToken();
+            return new SQLFlashbackExpr(SQLFlashbackExpr.Type.TIMESTAMP, this.expr());
         }
     }
 

src/main/java/com/alibaba/druid/sql/dialect/oracle/visitor/OracleASTVisitor.java

@@ -19,9 +19,6 @@ import com.alibaba.druid.sql.dialect.oracle.ast.OracleDataTypeIntervalDay;
 import com.alibaba.druid.sql.dialect.oracle.ast.OracleDataTypeIntervalYear;
 import com.alibaba.druid.sql.dialect.oracle.ast.OracleDataTypeTimestamp;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.CycleClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause.AsOfFlashbackQueryClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause.AsOfSnapshotClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause.VersionsFlashbackQueryClause;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.ModelClause;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.OracleLobStorageClause;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.OracleReturningClause;
@@ -129,14 +126,6 @@ public interface OracleASTVisitor extends SQLASTVisitor {
 
     void endVisit(PartitionExtensionClause x);
 
-    boolean visit(VersionsFlashbackQueryClause x);
-
-    void endVisit(VersionsFlashbackQueryClause x);
-
-    boolean visit(AsOfFlashbackQueryClause x);
-
-    void endVisit(AsOfFlashbackQueryClause x);
-
     boolean visit(OracleWithSubqueryEntry x);
 
     void endVisit(OracleWithSubqueryEntry x);
@@ -353,10 +342,6 @@ public interface OracleASTVisitor extends SQLASTVisitor {
 
     void endVisit(OracleAlterViewStatement x);
 
-    boolean visit(AsOfSnapshotClause x);
-
-    void endVisit(AsOfSnapshotClause x);
-
     boolean visit(OracleAlterTableMoveTablespace x);
 
     void endVisit(OracleAlterTableMoveTablespace x);

src/main/java/com/alibaba/druid/sql/dialect/oracle/visitor/OracleASTVisitorAdapter.java

@@ -21,9 +21,6 @@ import com.alibaba.druid.sql.dialect.oracle.ast.OracleDataTypeIntervalDay;
 import com.alibaba.druid.sql.dialect.oracle.ast.OracleDataTypeIntervalYear;
 import com.alibaba.druid.sql.dialect.oracle.ast.OracleDataTypeTimestamp;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.CycleClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause.AsOfFlashbackQueryClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause.AsOfSnapshotClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause.VersionsFlashbackQueryClause;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.ModelClause;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.ModelClause.CellAssignment;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.ModelClause.CellAssignmentItem;
@@ -263,28 +260,6 @@ public class OracleASTVisitorAdapter extends SQLASTVisitorAdapter implements Ora
 
     }
 
-    @Override
-    public boolean visit(VersionsFlashbackQueryClause x) {
-
-        return true;
-    }
-
-    @Override
-    public void endVisit(VersionsFlashbackQueryClause x) {
-
-    }
-
-    @Override
-    public boolean visit(AsOfFlashbackQueryClause x) {
-
-        return true;
-    }
-
-    @Override
-    public void endVisit(AsOfFlashbackQueryClause x) {
-
-    }
-
     @Override
     public boolean visit(OracleWithSubqueryEntry x) {
 
@@ -840,16 +815,6 @@ public class OracleASTVisitorAdapter extends SQLASTVisitorAdapter implements Ora
 
     }
 
-    @Override
-    public boolean visit(AsOfSnapshotClause x) {
-        return true;
-    }
-
-    @Override
-    public void endVisit(AsOfSnapshotClause x) {
-
-    }
-
     @Override
     public boolean visit(OracleAlterViewStatement x) {
         return true;

src/main/java/com/alibaba/druid/sql/dialect/oracle/visitor/OracleOutputVisitor.java

@@ -18,20 +18,13 @@ package com.alibaba.druid.sql.dialect.oracle.visitor;
 import java.util.List;
 
 import com.alibaba.druid.sql.ast.*;
-import com.alibaba.druid.sql.ast.expr.SQLAllColumnExpr;
-import com.alibaba.druid.sql.ast.expr.SQLCharExpr;
-import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
-import com.alibaba.druid.sql.ast.expr.SQLLiteralExpr;
-import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
+import com.alibaba.druid.sql.ast.expr.*;
 import com.alibaba.druid.sql.ast.statement.*;
 import com.alibaba.druid.sql.ast.statement.SQLJoinTableSource.JoinType;
 import com.alibaba.druid.sql.dialect.oracle.ast.OracleDataTypeIntervalDay;
 import com.alibaba.druid.sql.dialect.oracle.ast.OracleDataTypeIntervalYear;
 import com.alibaba.druid.sql.dialect.oracle.ast.OracleDataTypeTimestamp;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.CycleClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause.AsOfFlashbackQueryClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause.AsOfSnapshotClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause.VersionsFlashbackQueryClause;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.ModelClause;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.ModelClause.CellAssignment;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.ModelClause.CellAssignmentItem;
@@ -308,10 +301,7 @@ public class OracleOutputVisitor extends SQLASTOutputVisitor implements OracleAS
                 print(')');
             }
 
-            if (x.getFlashback() != null) {
-                println();
-                x.getFlashback().accept(this);
-            }
+            printFlashback(x.getFlashback());
         }
 
         return false;
@@ -489,10 +479,7 @@ public class OracleOutputVisitor extends SQLASTOutputVisitor implements OracleAS
             x.getPivot().accept(this);
         }
 
-        if (x.getFlashback() != null) {
-            println();
-            x.getFlashback().accept(this);
-        }
+        printFlashback(x.getFlashback());
 
         if ((x.getAlias() != null) && (x.getAlias().length() != 0)) {
             print(' ');
@@ -536,16 +523,28 @@ public class OracleOutputVisitor extends SQLASTOutputVisitor implements OracleAS
             x.getPivot().accept(this);
         }
 
-        if (x.getFlashback() != null) {
-            println();
-            x.getFlashback().accept(this);
-        }
+        printFlashback(x.getFlashback());
 
         printAlias(x.getAlias());
 
         return false;
     }
 
+    private void printFlashback(SQLExpr flashback) {
+        if (flashback == null) {
+            return;
+        }
+
+        println();
+
+        if (flashback instanceof SQLBetweenExpr) {
+            flashback.accept(this);
+        } else {
+            print0(ucase ? "AS OF " : "as of ");
+            flashback.accept(this);
+        }
+    }
+
     public boolean visit(OracleSelectUnPivot x) {
         print0(ucase ? "UNPIVOT" : "unpivot");
         if (x.getNullsIncludeType() != null) {
@@ -768,36 +767,36 @@ public class OracleOutputVisitor extends SQLASTOutputVisitor implements OracleAS
 
     }
 
-    @Override
-    public boolean visit(VersionsFlashbackQueryClause x) {
-        print0(ucase ? "VERSIONS BETWEEN " : "versions between ");
-        print0(x.getType().name());
-        print(' ');
-        x.getBegin().accept(this);
-        print0(ucase ? " AND " : " and ");
-        x.getEnd().accept(this);
-        return false;
-    }
-
-    @Override
-    public void endVisit(VersionsFlashbackQueryClause x) {
-
-    }
-
-    @Override
-    public boolean visit(AsOfFlashbackQueryClause x) {
-        print0(ucase ? "AS OF " : "as of ");
-        print0(x.getType().name());
-        print0(" (");
-        x.getExpr().accept(this);
-        print(')');
-        return false;
-    }
-
-    @Override
-    public void endVisit(AsOfFlashbackQueryClause x) {
-
-    }
+//    @Override
+//    public boolean visit(VersionsFlashbackQueryClause x) {
+//        print0(ucase ? "VERSIONS BETWEEN " : "versions between ");
+//        print0(x.getType().name());
+//        print(' ');
+//        x.getBegin().accept(this);
+//        print0(ucase ? " AND " : " and ");
+//        x.getEnd().accept(this);
+//        return false;
+//    }
+//
+//    @Override
+//    public void endVisit(VersionsFlashbackQueryClause x) {
+//
+//    }
+//
+//    @Override
+//    public boolean visit(AsOfFlashbackQueryClause x) {
+//        print0(ucase ? "AS OF " : "as of ");
+//        print0(x.getType().name());
+//        print0(" (");
+//        x.getExpr().accept(this);
+//        print(')');
+//        return false;
+//    }
+//
+//    @Override
+//    public void endVisit(AsOfFlashbackQueryClause x) {
+//
+//    }
 
     @Override
     public boolean visit(OracleWithSubqueryEntry x) {
@@ -2288,18 +2287,18 @@ public class OracleOutputVisitor extends SQLASTOutputVisitor implements OracleAS
 
     }
 
-    @Override
-    public boolean visit(AsOfSnapshotClause x) {
-        print0(ucase ? "AS OF SNAPSHOT(" : "as of snapshot(");
-        x.getExpr().accept(this);
-        print(')');
-        return false;
-    }
-
-    @Override
-    public void endVisit(AsOfSnapshotClause x) {
-
-    }
+//    @Override
+//    public boolean visit(AsOfSnapshotClause x) {
+//        print0(ucase ? "AS OF SNAPSHOT(" : "as of snapshot(");
+//        x.getExpr().accept(this);
+//        print(')');
+//        return false;
+//    }
+//
+//    @Override
+//    public void endVisit(AsOfSnapshotClause x) {
+//
+//    }
 
     @Override
     public boolean visit(OracleAlterViewStatement x) {

src/main/java/com/alibaba/druid/sql/dialect/oracle/visitor/OracleSchemaStatVisitor.java

@@ -35,9 +35,6 @@ import com.alibaba.druid.sql.dialect.oracle.ast.OracleDataTypeIntervalDay;
 import com.alibaba.druid.sql.dialect.oracle.ast.OracleDataTypeIntervalYear;
 import com.alibaba.druid.sql.dialect.oracle.ast.OracleDataTypeTimestamp;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.CycleClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause.AsOfFlashbackQueryClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause.AsOfSnapshotClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause.VersionsFlashbackQueryClause;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.ModelClause;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.ModelClause.CellAssignment;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.ModelClause.CellAssignmentItem;
@@ -492,28 +489,6 @@ public class OracleSchemaStatVisitor extends SchemaStatVisitor implements Oracle
 
     }
 
-    @Override
-    public boolean visit(VersionsFlashbackQueryClause x) {
-
-        return true;
-    }
-
-    @Override
-    public void endVisit(VersionsFlashbackQueryClause x) {
-
-    }
-
-    @Override
-    public boolean visit(AsOfFlashbackQueryClause x) {
-
-        return true;
-    }
-
-    @Override
-    public void endVisit(AsOfFlashbackQueryClause x) {
-
-    }
-
     @Override
     public boolean visit(OracleWithSubqueryEntry x) {
         Map<String, String> aliasMap = getAliasMap();
@@ -1184,16 +1159,6 @@ public class OracleSchemaStatVisitor extends SchemaStatVisitor implements Oracle
 
     }
 
-    @Override
-    public boolean visit(AsOfSnapshotClause x) {
-        return false;
-    }
-
-    @Override
-    public void endVisit(AsOfSnapshotClause x) {
-
-    }
-
     @Override
     public boolean visit(OracleAlterViewStatement x) {
         return false;

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

@@ -4485,4 +4485,18 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
 
         return false;
     }
+
+    public boolean visit(SQLFlashbackExpr x) {
+        print0(x.getType().name());
+        print(' ');
+        SQLExpr expr = x.getExpr();
+        if (expr instanceof SQLBinaryOpExpr) {
+            print('(');
+            expr.accept(this);
+            print(')');
+        } else {
+            expr.accept(this);
+        }
+        return false;
+    }
 }

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

@@ -726,4 +726,10 @@ public interface SQLASTVisitor {
     boolean visit(SQLCommitStatement x);
 
     void endVisit(SQLCommitStatement x);
+
+
+    boolean visit(SQLFlashbackExpr x);
+
+    void endVisit(SQLFlashbackExpr x);
+    //
 }

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

@@ -1643,7 +1643,6 @@ public class SQLASTVisitorAdapter implements SQLASTVisitor {
 
     }
 
-
     @Override
     public boolean visit(SQLCommitStatement x) {
         return true;
@@ -1653,4 +1652,14 @@ public class SQLASTVisitorAdapter implements SQLASTVisitor {
     public void endVisit(SQLCommitStatement x) {
 
     }
+
+    @Override
+    public boolean visit(SQLFlashbackExpr x) {
+        return true;
+    }
+
+    @Override
+    public void endVisit(SQLFlashbackExpr x) {
+
+    }
 }

src/test/java/com/alibaba/druid/bvt/sql/mysql/MySqlSetTest_3.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 1999-2017 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.alibaba.druid.bvt.sql.mysql;
+
+import com.alibaba.druid.sql.SQLUtils;
+import com.alibaba.druid.sql.ast.SQLStatement;
+import com.alibaba.druid.sql.dialect.mysql.parser.MySqlStatementParser;
+import com.alibaba.druid.sql.dialect.mysql.visitor.MySqlSchemaStatVisitor;
+import junit.framework.TestCase;
+import org.junit.Assert;
+
+import java.util.List;
+
+public class MySqlSetTest_3 extends TestCase {
+
+    public void test_0() throws Exception {
+        String sql = "SET sql_mode=?,NAMES ?,CHARACTER SET utf8,CHARACTER_SET_RESULTS=utf8,COLLATION_CONNECTION=?";
+
+        MySqlStatementParser parser = new MySqlStatementParser(sql);
+        List<SQLStatement> stmtList = parser.parseStatementList();
+        SQLStatement stmt = stmtList.get(0);
+//        print(stmtList);
+
+        Assert.assertEquals(1, stmtList.size());
+
+        MySqlSchemaStatVisitor visitor = new MySqlSchemaStatVisitor();
+        stmt.accept(visitor);
+
+//        System.out.println("Tables : " + visitor.getTables());
+//        System.out.println("fields : " + visitor.getColumns());
+//        System.out.println("coditions : " + visitor.getConditions());
+//        System.out.println("orderBy : " + visitor.getOrderByColumns());
+
+        Assert.assertEquals(0, visitor.getTables().size());
+        Assert.assertEquals(0, visitor.getColumns().size());
+        Assert.assertEquals(0, visitor.getConditions().size());
+
+        String text = SQLUtils.toMySqlString(stmt);
+
+        Assert.assertEquals("SET sql_mode = ?, NAMES ?, CHARACTER SET utf8, CHARACTER_SET_RESULTS = utf8, COLLATION_CONNECTION = ?", text);
+    }
+}

src/test/java/com/alibaba/druid/bvt/sql/oracle/OracleFlashbackQueryTest2.java

@@ -31,7 +31,7 @@ public class OracleFlashbackQueryTest2 extends TestCase {
 
         String expect = "SELECT salary\n"
                         + "FROM employees\n"
-                        + "VERSIONS BETWEEN TIMESTAMP SYSTIMESTAMP - INTERVAL '10' MINUTE AND SYSTIMESTAMP - INTERVAL '1' MINUTE\n"
+                        + "VERSIONS BETWEEN TIMESTAMP (SYSTIMESTAMP - INTERVAL '10' MINUTE) AND SYSTIMESTAMP - INTERVAL '1' MINUTE\n"
                         + "WHERE last_name = 'Chung';";
 
         OracleStatementParser parser = new OracleStatementParser(sql);

src/test/java/com/alibaba/druid/bvt/sql/oracle/OracleFlashbackQueryTest4.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 1999-2017 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.alibaba.druid.bvt.sql.oracle;
+
+import com.alibaba.druid.sql.ast.statement.SQLSelectStatement;
+import com.alibaba.druid.sql.dialect.oracle.parser.OracleStatementParser;
+import com.alibaba.druid.sql.test.TestUtils;
+import junit.framework.TestCase;
+import org.junit.Assert;
+
+public class OracleFlashbackQueryTest4 extends TestCase {
+
+    public void test_isEmpty() throws Exception {
+        String sql = "SELECT * FROM employees\n" +
+                "AS OF TIMESTAMP\n" +
+                "TO_TIMESTAMP('2004-04-04 09:30:00', 'YYYY-MM-DD HH:MI:SS')\n" +
+                "WHERE last_name = 'Chung';";
+
+        String expect = "SELECT *\n" +
+                "FROM employees\n" +
+                "AS OF TIMESTAMP TO_TIMESTAMP('2004-04-04 09:30:00', 'YYYY-MM-DD HH:MI:SS')\n" +
+                "WHERE last_name = 'Chung';";
+
+        OracleStatementParser parser = new OracleStatementParser(sql);
+        SQLSelectStatement stmt = (SQLSelectStatement) parser.parseStatementList().get(0);
+
+        String text = TestUtils.outputOracle(stmt);
+
+        Assert.assertEquals(expect, text);
+
+        System.out.println(text);
+    }
+}

src/test/java/com/alibaba/druid/bvt/sql/oracle/visitor/OracleASTVisitorAdapterTest.java

@@ -10,9 +10,6 @@ import com.alibaba.druid.sql.dialect.oracle.ast.OracleDataTypeIntervalDay;
 import com.alibaba.druid.sql.dialect.oracle.ast.OracleDataTypeIntervalYear;
 import com.alibaba.druid.sql.dialect.oracle.ast.OracleDataTypeTimestamp;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.CycleClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause.AsOfFlashbackQueryClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause.AsOfSnapshotClause;
-import com.alibaba.druid.sql.dialect.oracle.ast.clause.FlashbackQueryClause.VersionsFlashbackQueryClause;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.ModelClause;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.ModelClause.CellAssignment;
 import com.alibaba.druid.sql.dialect.oracle.ast.clause.ModelClause.CellAssignmentItem;
@@ -105,9 +102,6 @@ public class OracleASTVisitorAdapterTest extends TestCase {
         new OracleSelectUnPivot().accept(adapter);
         new SQLTimestampExpr().accept(adapter);
         new PartitionExtensionClause().accept(adapter);
-        new VersionsFlashbackQueryClause().accept(adapter);
-        new VersionsFlashbackQueryClause().accept(adapter);
-        new AsOfFlashbackQueryClause().accept(adapter);
         new SQLGroupingSetExpr().accept(adapter);
         new OracleWithSubqueryEntry().accept(adapter);
         new OracleFileSpecification().accept(adapter);
@@ -188,7 +182,6 @@ public class OracleASTVisitorAdapterTest extends TestCase {
         new SQLCommitStatement().accept(adapter);
         new OracleAlterTriggerStatement().accept(adapter);
         new OracleAlterSynonymStatement().accept(adapter);
-        new AsOfSnapshotClause().accept(adapter);
         new OracleAlterViewStatement().accept(adapter);
         new OracleAlterTableMoveTablespace().accept(adapter);
         new OracleSizeExpr().accept(adapter);