Optimize escaping SQL

[nwoltman]

In today's V8, appending to a string is faster than building an array and calling .join().

Benchmark

$ npm install benchmark

'use strict';

var Benchmark = require('benchmark');
var SqlString = require('mysql/lib/protocol/SqlString');

var ids = ['id', 'name'];
var arrays = [['value', 12]];
var object = {
  id: 1,
  name: 'Some Name',
  email: 'somename@email.com',
  parentId: 20,
  notify: true,
};

new Benchmark.Suite()
  .add('escapeId', () => {
    SqlString.escapeId(ids);
  })
  .add('escape arrays', () => {
    SqlString.escape(arrays);
  })
  .add('escape object', () => {
    SqlString.escape(object);
  })
  .on('cycle', function(event) {
    console.log(String(event.target));
  })
  .run();

Results:

Test	Before (ops/sec)	After (ops/sec)	Speedup
escapeId	1,260,802	1,771,151	40% (1.4x)
escape arrays	1,037,337	2,384,038	130% (2.3x)
escape object	279,876	456,599	63% (1.63x)

[dougwilson]

The change from SqlString.escapeId to just escapeId will affect people who are using AOP around this function, since we have been calling it as a method. Just noting this if you wonder why that part is reverted in the merge of your pull request.