fix pagination query offset, and also change order by transaction_id from nothing (ASC) to DESC

lib/api.js

@@ -423,9 +423,9 @@ app.get('/pool/payments/:pool_type', function (req, res) {
             return res.json({'error': 'Invalid pool type'});
     }
     let paymentIds = [];
-    let query = "SELECT distinct(transaction_id) as txnID FROM payments WHERE pool_type = ? ORDER BY transaction_id LIMIT ? OFFSET ?";
+    let query = "SELECT distinct(transaction_id) as txnID FROM payments WHERE pool_type = ? ORDER BY transaction_id DESC LIMIT ? OFFSET ?";
     let response = [];
-    global.mysql.query(query, [pool_type, limit, page]).then(function (rows) {
+    global.mysql.query(query, [pool_type, limit, page * limit]).then(function (rows) {
         if (rows.length === 0) {
             return res.json([]);
         }