How to calculate sum of column in sql using flutter

Question

I'm trying to calculate the sum of TotalPrice column in my table Items but it returns a null(waiting ...) in a text widget according to the condition I've given.

 Future calculateTotal(var order) async {
var dbClient = db;
var result = await dbClient.rawQuery(
    'select sum(TotalPrice) as Total from Items where refID = ?'[order]);

print(result.toList());

}

*above is the code in my database helper class**

    double _total;
  void _calcTotal() async {
    var total =
        (await OrderProvider().calculateTotal(widget.order))[0]['Total'];
    print(total);
    setState(() {
      _total = total;
    });
  }

  Widget showItems() {
    return Container(
      color: Colors.blueGrey,
      child: Column(
        children: <Widget>[
          Container(
              color: Colors.amberAccent,
              padding: EdgeInsets.only(
                top: 10,
                bottom: 10,
              ),
              child: Center(
                child: Text(
                  _total != null ? _total : 'waiting ...',
                  style: TextStyle(fontSize: 10),
                ),
              )),

above is the code in my widget class. I've used this example I've used this example

ryan chege · Accepted Answer · 2020-06-12 18:49:15Z

0

I added a comma in my future method in the database provider class

    Future calculateTotal(var order) async {
var dbClient = db;
var result = await dbClient.rawQuery(
    'select sum(TotalPrice) as Total from Items where refID = ?',[order]);

print(result.toList());

I also forgot to include quotation marks in my text widget,

Widget showItems() {
return Container(
  color: Colors.blueGrey,
  child: Column(
    children: <Widget>[
      Container(
          color: Colors.amberAccent,
          padding: EdgeInsets.only(
            top: 10,
            bottom: 10,
          ),
          child: Center(
            child: Text("
              _total != null ? _total : 'waiting ..."',
              style: TextStyle(fontSize: 10),
            ),
          )),

answered Jun 12, 2020 at 18:49

ryan chege

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