support oracle connect_by_root

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

@@ -23,6 +23,7 @@ public class SQLSelectItem extends SQLObjectImpl {
 
     private SQLExpr expr;
     private String  alias;
+    private boolean connectByRoot = false;
 
     public SQLSelectItem(){
 
@@ -40,6 +41,16 @@ public class SQLSelectItem extends SQLObjectImpl {
             expr.setParent(this);
         }
     }
+    
+    public SQLSelectItem(SQLExpr expr, String alias, boolean connectByRoot){
+        this.connectByRoot = connectByRoot;
+        this.expr = expr;
+        this.alias = alias;
+        
+        if (expr != null) {
+            expr.setParent(this);
+        }
+    }
 
     public SQLExpr getExpr() {
         return this.expr;
@@ -61,6 +72,9 @@ public class SQLSelectItem extends SQLObjectImpl {
     }
 
     public void output(StringBuffer buf) {
+        if(this.connectByRoot) {
+            buf.append(" CONNECT_BY_ROOT ");
+        }
         this.expr.output(buf);
         if ((this.alias != null) && (this.alias.length() != 0)) {
             buf.append(" AS ");
@@ -99,4 +113,12 @@ public class SQLSelectItem extends SQLObjectImpl {
         return true;
     }
 
+    public boolean isConnectByRoot() {
+        return connectByRoot;
+    }
+
+    public void setConnectByRoot(boolean connectByRoot) {
+        this.connectByRoot = connectByRoot;
+    }
+
 }

src/main/java/com/alibaba/druid/sql/parser/SQLSelectParser.java

@@ -284,7 +284,12 @@ public class SQLSelectParser extends SQLParser {
 
     protected SQLSelectItem parseSelectItem() {
         SQLExpr expr;
+        boolean connectByRoot = false;
         if (lexer.token() == Token.IDENTIFIER) {
+            if (identifierEquals("CONNECT_BY_ROOT")) {
+                connectByRoot = true;
+                lexer.nextToken();
+            }
             expr = new SQLIdentifierExpr(lexer.stringVal());
             lexer.nextTokenComma();
 
@@ -297,7 +302,7 @@ public class SQLSelectParser extends SQLParser {
         }
         final String alias = as();
 
-        return new SQLSelectItem(expr, alias);
+        return new SQLSelectItem(expr, alias, connectByRoot);
     }
 
     public void parseFrom(SQLSelectQueryBlock queryBlock) {

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

@@ -697,6 +697,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Printab
     }
 
     public boolean visit(SQLSelectItem x) {
+        if(x.isConnectByRoot()) {
+            print("CONNECT_BY_ROOT ");
+        }
         x.getExpr().accept(this);
 
         if ((x.getAlias() != null) && (x.getAlias().length() > 0)) {