sequence of select query not right - sqlite

Question

I tried to query my database for data. However, when I query for my data, I only managed to get the data after my last alert, which is the alert("Total...") For instance, I run the code below, the alert for "result row:" only appear after the last alert appear. May I know why?
function (result) {
window.location.href = "#/app/CustHomePage";
var totalBalance = 0;
var tableRef = document.getElementById("myList").getElementsByTagName("tbody")[0];
for (var i = 0; i < tableRef.rows.length; i++) {
alert(tableRef.rows[i].cells[3].innerHTML.substr(1));
var addBalance = parseInt(tableRef.rows[i].cells[3].innerHTML.substr(1));
totalBalance = totalBalance + addBalance;
}
alert(totalBalance);
var myText = result.text;
var myTextTwo = myText.replace(/['"]+/g, '');
alert(myTextTwo);
var custBal;
var myDB = window.sqlitePlugin.openDatabase({ name: "mySQLite.db", location: 'default' });
alert("Hello");
myDB.transaction(function(transaction) {
alert("Hello");
transaction.executeSql("SELECT customerBalance FROM customer where nric = '" + myTextTwo + "'", [], function (tx, results) {
var len = results.rows.length;
for (var i = 0; i < len; i++) {
custBal = results.rows.item(i).customerBalance;
alert("result row" + results.rows.item(i).customerBalance);
alert("CustomerBal" + custBal);
}
},
function(tx, error)
{
}
);
});
alert("Total after entitled discount: ");
alert("Transaction successful, Next Customer Please");
}

Answer 1

Move anything you want to happen after the DB transaction has returned or failed in either the success or error handlers, I just moved them out of the arguments and gave them names to keep track of them. and then added your comment to the end of the successCallback handler. Anything you want to happen after a transaction was not successful use the error callback.
function successCallback(tx, results) {
var len = results.rows.length;
for (var i = 0; i < len; i++) {
custBal = results.rows.item(i).customerBalance;
alert("result row" + results.rows.item(i).customerBalance);
alert("CustomerBal" + custBal);
}
alert("Total after entitled discount: ");
alert("Transaction successful, Next Customer Please");
}
function errorCallback(tx, error) {
}
myDB.transaction(function (transaction) {
alert("Hello");
transaction.executeSql("SELECT customerBalance FROM customer where nric = '" + myTextTwo + "'", [], successCallback, errorCallback);
});