array is outside from my for-loop empty nodejs

I would like with my array works outside of my for loop but my array is empty:

let dataSitesIndex = [];
            for(let i = 1; i <= dataMainIndexLength; i++){
                pdo.query("SELECT * FROM subsites WHERE main = ?",[i] , function(err, result, fields) {
                    dataSitesIndex[i] = result;
                    console.log(result);
                })
            }

let dataLength = async function(){
    try {
        //Durchsuchen der Nachrichtenseite, speichern der MainID
        pdo.query(`SELECT * FROM mainsites`, function(err, result, fields) {
            let results = result;
            let resultsLength = results.length;


            //MainID
            let dataIndexMainId = [];
            for(let index = 0; index < resultsLength; index++){
                dataIndexMainId[index] = results[index]["id"];
            }


            let dataMainIndexLength = dataIndexMainId.length;

            let dataSitesIndex = [];
            for(let i = 1; i <= dataMainIndexLength; i++){
                pdo.query("SELECT * FROM subsites WHERE main = ?",[i] , function(err, result, fields) {
                    dataSitesIndex[i] = result;
                    console.log(result);
                })
            }


        })
    } catch(error) {
        console.log(error)
    }
}