let columnsArray = ['col1', 'col2'];
let tablesArray = ['table1', 'table2'];

}).then(result => {
   // some code

   // HELP Required
   for(i=0; i<2; i++) {
     return pool.request()
     .query("SELECT " + COL[i] + " FROM " + TABLE[i]) // returns a promise
   }
}).then(result = {
   console.log(result.recordsets)
})