Promise handling a database call

database-promise.js

const queryADatabase = function(mysql, query) {
  return new Promise((resolve, reject) => {
    mysql.query(query, (err, rows) => {
      if (err) reject(err);
      else resolve(rows);
    });
  })
};

/* What we're doing here is creating a promise that resolves or rejects 
based on the outcome of an SQL query. Breaking it down, our outermost function
takes a database instance and an SQL query. That function will return a promise. 
That promise will reject if the SQL query throws and resolve (returning the 
database info) if the query goes through successfully. */