Update SQL.md (#139)

* Update SQL.md

untested, I didn't see db.parallelize in the API https://github.com/mapbox/node-sqlite3/wiki/API

* Remove reference to the removed parallelize method

* Keep Error fallback

* Preserve formatting

Author: caub

examples/SQL.md

@@ -5,41 +5,24 @@ While not a key-value store, SQL offers a natural batch mechanism with
 stores, it is still suited for SQL when queries remain simple. This example
 requests the entire row at a given `id`, however your usage may differ.
 
-This example uses the [sqlite3][] client which offers a `parallelize` method to
-further batch queries together. Another non-caching `DataLoader` utilizes this
-method to provide a similar API. `DataLoaders` can access other `DataLoaders`.
-
 ```js
 const DataLoader = require('dataloader')
 const sqlite3 = require('sqlite3')
 
 const db = new sqlite3.Database('./to/your/db.sql')
 
 // Dispatch a WHERE-IN query, ensuring response has rows in correct order.
-const userLoader = new DataLoader(async ids => {
-  const params = ids.map(id => '?' ).join()
-  const query = `SELECT * FROM users WHERE id IN (${params})`
-  const rows = await queryLoader.load([query, ids])
-  return ids.map(
-    id => rows.find(row => row.id === id) || new Error(`Row not found: ${id}`)
-  )
-})
-
-// Parallelize all queries, but do not cache.
-const queryLoader = new DataLoader(queries => new Promise(resolve => {
-  const waitingOn = queries.length
-  const results = []
-  db.parallelize(() => {
-    queries.forEach((query, index) => {
-      db.all.apply(db, query.concat((error, result) => {
-        results[index] = error || result
-        if (--waitingOn === 0) {
-          resolve(results)
-        }
-      }))
-    })
-  })
-}), { cache: false })
+const userLoader = new DataLoader(ids => new Promise((resolve, reject) => {
+  db.all('SELECT * FROM users WHERE id IN $ids', {$ids: ids}, (error, rows) => {
+    if (error) {
+      reject(error);
+    } else {
+      resolve(ids.map(
+        id => rows.find(row => rows.id === id) || new Error(`Row not found: ${id}`)
+      ));
+    }
+  });
+}));
 
 // Usage