improved sql parser.

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

@@ -35,6 +35,8 @@ public class SQLBinaryOpExpr extends SQLExprImpl implements SQLReplaceable, Seri
     private SQLBinaryOperator operator;
     private String            dbType;
 
+    private boolean          bracket  = false;
+
     public SQLBinaryOpExpr(){
 
     }
@@ -99,6 +101,14 @@ public class SQLBinaryOpExpr extends SQLExprImpl implements SQLReplaceable, Seri
         this.operator = operator;
     }
 
+    public boolean isBracket() {
+        return bracket;
+    }
+
+    public void setBracket(boolean bracket) {
+        this.bracket = bracket;
+    }
+
     protected void accept0(SQLASTVisitor visitor) {
         if (visitor.visit(this)) {
             acceptChild(visitor, this.left);

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

@@ -87,4 +87,14 @@ public class SQLQueryExpr extends SQLExprImpl implements Serializable {
         }
         return true;
     }
+
+    public SQLQueryExpr clone() {
+        SQLQueryExpr x = new SQLQueryExpr();
+
+        if (subQuery != null) {
+            x.setSubQuery(subQuery.clone());
+        }
+
+        return x;
+    }
 }

src/main/java/com/alibaba/druid/sql/dialect/db2/visitor/DB2OutputVisitor.java

@@ -43,9 +43,6 @@ public class DB2OutputVisitor extends SQLASTOutputVisitor implements DB2ASTVisit
         if (x.isForReadOnly()) {
             println();
             print0(ucase ? "FOR READ ONLY" : "for read only");
-        } else if (x.isForUpdate()) {
-            println();
-            print0(ucase ? "FOR UPDATE" : "for update");
         }
 
         if (x.getIsolation() != null) {

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

@@ -1695,7 +1695,7 @@ public class OracleStatementParser extends SQLStatementParser {
         if (lexer.token() == Token.ALL) {
             lexer.nextToken();
             stmt.setOption(OracleMultiInsertStatement.Option.ALL);
-        } else if (lexer.token() == Token.FIRST) {
+        } else if (lexer.token() == Token.FIRST || identifierEquals("FIRST")) {
             lexer.nextToken();
             stmt.setOption(OracleMultiInsertStatement.Option.FIRST);
         }

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

@@ -144,8 +144,11 @@ public class OracleOutputVisitor extends SQLASTOutputVisitor implements OracleAS
     }
 
     public boolean visit(OracleDbLinkExpr x) {
-        x.getExpr().accept(this);
-        print('@');
+        SQLExpr expr = x.getExpr();
+        if (expr != null) {
+            expr.accept(this);
+            print('@');
+        }
         print0(x.getDbLink());
         return false;
     }

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

@@ -228,6 +228,10 @@ public class SQLExprParser extends SQLParser {
 
                     sqlExpr = listExpr;
                 }
+
+                if (sqlExpr instanceof SQLBinaryOpExpr) {
+                    ((SQLBinaryOpExpr) sqlExpr).setBracket(true);
+                }
                 
                 accept(Token.RPAREN);
                 break;

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

@@ -33,6 +33,7 @@ import com.alibaba.druid.sql.ast.statement.SQLCreateTriggerStatement.TriggerEven
 import com.alibaba.druid.sql.ast.statement.SQLCreateTriggerStatement.TriggerType;
 import com.alibaba.druid.sql.dialect.mysql.ast.clause.MySqlRepeatStatement;
 import com.alibaba.druid.util.JdbcConstants;
+import com.alibaba.druid.util.JdbcUtils;
 
 public class SQLStatementParser extends SQLParser {
 
@@ -129,6 +130,14 @@ public class SQLStatementParser extends SQLParser {
 
                     continue;
                 }
+                case WITH:
+                if (!JdbcConstants.POSTGRESQL.equals(dbType)){
+                    SQLStatement stmt = parseSelect();
+                    stmt.setParent(parent);
+                    statementList.add(stmt);
+                    continue;
+                }
+                break;
                 case SELECT: {
                     SQLStatement stmt = parseSelect();
                     stmt.setParent(parent);

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

@@ -476,10 +476,17 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
 
         if (x.getRight() instanceof SQLBinaryOpExpr) {
             SQLBinaryOpExpr right = (SQLBinaryOpExpr) x.getRight();
-            boolean rightRational = right.getOperator() == SQLBinaryOperator.BooleanAnd
-                                    || right.getOperator() == SQLBinaryOperator.BooleanOr;
+            SQLBinaryOperator rightOp = right.getOperator();
+            SQLBinaryOperator op = x.getOperator();
+            boolean rightRational = rightOp == SQLBinaryOperator.BooleanAnd
+                                    || rightOp == SQLBinaryOperator.BooleanOr;
 
-            if (right.getOperator().priority >= x.getOperator().priority) {
+            if (rightOp.priority >= op.priority
+                    || (right.isBracket()
+                    && rightOp != op
+                    && rightOp.isLogical()
+                    && op.isLogical()
+            )) {
                 if (rightRational) {
                     incrementIndent();
                 }
@@ -507,10 +514,16 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
     private void visitBinaryLeft(SQLExpr left, SQLBinaryOperator op) {
         if (left instanceof SQLBinaryOpExpr) {
             SQLBinaryOpExpr binaryLeft = (SQLBinaryOpExpr) left;
-            boolean leftRational = binaryLeft.getOperator() == SQLBinaryOperator.BooleanAnd
-                                   || binaryLeft.getOperator() == SQLBinaryOperator.BooleanOr;
+            SQLBinaryOperator leftOp = binaryLeft.getOperator();
+            boolean leftRational = leftOp == SQLBinaryOperator.BooleanAnd
+                                   || leftOp == SQLBinaryOperator.BooleanOr;
 
-            if (binaryLeft.getOperator().priority > op.priority) {
+            if (leftOp.priority > op.priority
+                    || (binaryLeft.isBracket()
+                        && leftOp != op
+                        && leftOp.isLogical()
+                        && op.isLogical()
+            )) {
                 if (leftRational) {
                     incrementIndent();
                 }