diff --git a/README.md b/README.md
index f530e05..716d26d 100644
--- a/README.md
+++ b/README.md
@@ -287,11 +287,12 @@ TBD
 
 ## APIs
 
-`*` Meaning this function is yieldable.
+- `*` Meaning this function is yieldable.
 
 ### IO queries
 
-- *query(sql[, values])
+- *query(sql[, values)
+- *queryOne(sql[, values)
 - *select(table, options)
 - *get(table, where, options)
 - *insert(table, row[s], options)
@@ -331,7 +332,7 @@ let session = new db.literals.Literal('session()');
 
 ## TODO
 
-- [ ] MySQL
+- [x] MySQL
   - [x] Pool
   - [ ] Cluster
 - [ ] SQL Server
diff --git a/lib/client.js b/lib/client.js
index 27aa5cd..c85183f 100644
--- a/lib/client.js
+++ b/lib/client.js
@@ -1,11 +1,3 @@
-/**
- * Copyright(c) ali-sdk and other contributors.
- * MIT Licensed
- *
- * Authors:
- *   fengmk2 <m@fengmk2.com> (http://fengmk2.com)
- */
-
 'use strict';
 
 /**
diff --git a/lib/connection.js b/lib/connection.js
index eeb35f4..bae5710 100644
--- a/lib/connection.js
+++ b/lib/connection.js
@@ -1,13 +1,3 @@
-/**!
- * ali-rds - lib/connection.js
- *
- * Copyright(c) ali-sdk and other contributors.
- * MIT Licensed
- *
- * Authors:
- *   fengmk2 <m@fengmk2.com> (http://fengmk2.com)
- */
-
 'use strict';
 
 /**
diff --git a/lib/literals.js b/lib/literals.js
index 41a7af8..f7bd471 100644
--- a/lib/literals.js
+++ b/lib/literals.js
@@ -1,13 +1,3 @@
-/**!
- * ali-rds - lib/literals.js
- *
- * Copyright(c) ali-sdk and other contributors.
- * MIT Licensed
- *
- * Authors:
- *   fengmk2 <m@fengmk2.com> (http://fengmk2.com)
- */
-
 'use strict';
 
 /**
diff --git a/lib/operator.js b/lib/operator.js
index a79cba4..7449313 100644
--- a/lib/operator.js
+++ b/lib/operator.js
@@ -1,13 +1,3 @@
-/**!
- * ali-rds - lib/operator.js
- *
- * Copyright(c) ali-sdk and other contributors.
- * MIT Licensed
- *
- * Authors:
- *   fengmk2 <m@fengmk2.com> (http://fengmk2.com)
- */
-
 'use strict';
 
 /**
@@ -20,9 +10,10 @@ const literals = require('./literals');
 
 module.exports = Operator;
 
-function Operator() {
-
-}
+/**
+ * Operator Interface
+ */
+function Operator() {}
 
 const proto = Operator.prototype;
 
@@ -40,14 +31,16 @@ proto.format = function (sql, values, stringifyObjects, timeZone) {
   return SqlString.format(sql, values, stringifyObjects, timeZone);
 };
 
-proto.query = function* (sql, values) {
+proto.query = function*(sql, values) {
   // query(sql, values)
   if (arguments.length >= 2) {
     sql = this.format(sql, values);
   }
   debug('query %j', sql);
   try {
-    return yield this._query(sql);
+    const rows = yield this._query(sql);
+    debug('query get %d rows', rows.length);
+    return rows;
   } catch (err) {
     err.stack = err.stack + '\n    sql: ' + sql;
     debug('query error: %s', err);
@@ -55,6 +48,11 @@ proto.query = function* (sql, values) {
   }
 };
 
+proto.queryOne = function*(sql, values) {
+  const rows = yield this.query(sql, values);
+  return rows && rows[0] || null;
+};
+
 proto._query = function (/* sql */) {
   throw new Error('SubClass must impl this');
 };
diff --git a/lib/sqlstring.js b/lib/sqlstring.js
index 1c0c796..9f8ada7 100644
--- a/lib/sqlstring.js
+++ b/lib/sqlstring.js
@@ -1,21 +1,11 @@
-/**!
- * ali-rds - lib/sqlstring.js
- *
- * Copyright(c) ali-sdk and other contributors.
- * MIT Licensed
- *
- * Authors:
- *   fengmk2 <m@fengmk2.com> (http://fengmk2.com)
- */
-
 'use strict';
 
 /**
  * Module dependencies.
  */
 
-var SqlString = require('mysql/lib/protocol/SqlString');
-var Literal = require('./literals').Literal;
+const SqlString = require('mysql/lib/protocol/SqlString');
+const Literal = require('./literals').Literal;
 
 module.exports = SqlString;
 
diff --git a/lib/transaction.js b/lib/transaction.js
index 58686ca..899bed4 100644
--- a/lib/transaction.js
+++ b/lib/transaction.js
@@ -1,11 +1,3 @@
-/**
- * Copyright(c) ali-sdk and other contributors.
- * MIT Licensed
- *
- * Authors:
- *   fengmk2 <m@fengmk2.com> (http://fengmk2.com)
- */
-
 'use strict';
 
 /**
diff --git a/package.json b/package.json
index b922676..39725b3 100644
--- a/package.json
+++ b/package.json
@@ -13,8 +13,8 @@
     "autod": "autod -w --prefix '~'"
   },
   "dependencies": {
-    "debug": "~2.2.0",
-    "mysql": "~2.10.2"
+    "debug": "^2.2.0",
+    "mysql": "^2.10.2"
   },
   "devDependencies": {
     "autod": "*",
diff --git a/test/client.test.js b/test/client.test.js
index 1cd55a7..f1f8df3 100644
--- a/test/client.test.js
+++ b/test/client.test.js
@@ -1,11 +1,3 @@
-/**
- * Copyright(c) ali-sdk and other contributors.
- * MIT Licensed
- *
- * Authors:
- *   fengmk2 <m@fengmk2.com> (http://fengmk2.com)
- */
-
 'use strict';
 
 /**
@@ -16,7 +8,7 @@ const assert = require('assert');
 const rds = require('../');
 const config = require('./config');
 
-describe('test/client.test.js', function () {
+describe('client.test.js', function () {
   const prefix = 'prefix-' + process.version + '-';
   const table = 'ali-sdk-test-user';
   before(function* () {
@@ -38,6 +30,13 @@ describe('test/client.test.js', function () {
       assert(rows);
       assert(Array.isArray(rows));
     });
+
+    it('should connection query one row', function* () {
+      let conn = yield this.db.getConnection();
+      let row = yield conn.queryOne('show tables');
+      conn.release();
+      assert(row);
+    });
   });
 
   describe('escape()', function () {
@@ -52,7 +51,7 @@ describe('test/client.test.js', function () {
     });
   });
 
-  describe('query()', function () {
+  describe('query(), queryOne()', function () {
     before(function* () {
       yield this.db.query('insert into ??(name, email, gmt_create, gmt_modified) \
         values(?, ?, now(), now())',
@@ -69,6 +68,12 @@ describe('test/client.test.js', function () {
       assert.equal(rows[0].name, prefix + 'fengmk2');
       assert.equal(rows[1].name, prefix + 'fengmk3');
     });
+
+    it('should select 1 row', function* () {
+      const row = yield this.db.queryOne('select * from ?? where email=? order by id',
+        [table, prefix + 'm@fengmk2.com']);
+      assert.equal(row.name, prefix + 'fengmk2');
+    });
   });
 
   describe('transactions', function () {
@@ -323,6 +328,11 @@ describe('test/client.test.js', function () {
             values(?, ?, now(), now())',
             [table, prefix + 'beginTransactionScopeCtx2', prefix + 'm@beginTransactionScopeCtx1.com']);
 
+          // test query one
+          const row = yield conn.queryOne('select * from ?? where name=?', [table, prefix + 'beginTransactionScopeCtx1']);
+          assert(row);
+          assert.equal(row.name, prefix + 'beginTransactionScopeCtx1');
+
           const fooResult = yield fooInsert();
           assert.equal(fooResult, true);
           const barResult = yield barInsert();
diff --git a/test/operator.test.js b/test/operator.test.js
index 36b0382..31ec999 100644
--- a/test/operator.test.js
+++ b/test/operator.test.js
@@ -1,11 +1,3 @@
-/**
- * Copyright(c) ali-sdk and other contributors.
- * MIT Licensed
- *
- * Authors:
- *   fengmk2 <m@fengmk2.com> (http://fengmk2.com)
- */
-
 'use strict';
 
 /**
diff --git a/test/sqlstring.test.js b/test/sqlstring.test.js
index 0795a4d..386de93 100644
--- a/test/sqlstring.test.js
+++ b/test/sqlstring.test.js
@@ -1,13 +1,3 @@
-/**!
- * ali-rds - test/sqlstring.test.js
- *
- * Copyright(c) ali-sdk and other contributors.
- * MIT Licensed
- *
- * Authors:
- *   fengmk2 <m@fengmk2.com> (http://fengmk2.com)
- */
-
 'use strict';
 
 /**