trouble writing Select query using nodejs

I have node.js script that runs every 5 minutes and insert's data into the below table. I am using timestamp datatype in IBM Db2 database to identify each row.

I am trying to write a query in node.js that will connect to this table and display data hourly basis. I am facing trouble understanding how do i pick the row because different hours in a day will have multiple rows since it runs every 5 minutes. I am trying to write a logic that will pick the first row of every hour in the table and display it. Thus one day will have 24 rows returned.

I can either pick the first row of each hour or do a mean calculation of each hour.However, i am confused how to write a query for that. Can someone help me understand what i should use ?

CREATE TABLE TOTALS(

  SQLDB_POOLED INT,
  SQLDB_MAX  INT,
  SQLDB_ASSIGNED INT,

  SQLDB_TIMESTAMP TIMESTAMP NOT NULL DEFAULT CURRENT TIMESTAMP  
  ) ;  

node.js

ibmdb.open(dsnString, function (err,conn) {

      if (err) return console.log(err);

      conn.query('select SQLDB_MAX,SQLDB_ASSIGNED,(SQLDB_ASSIGNED + SQLDB_POOLED) As SUMOFAP from TOTALS, function (err, data) {
        if (err) console.log(err);

        console.log(data);
        res.send(JSON.stringify(data));

        conn.close(function () {
          console.log('done');
        });
      });
    });