SQL Lite Querying, build an object with multiple results

[Steve]

I'm trying to build an object with multiple sqlite result sets, something along the lines of

table1 = result of ("SELECT * FROM table1");
table2 = result of ("SELECT * FROM table2");
table3 = result of ("SELECT * FROM table3");
table4 = result of ("SELECT * FROM table4");

var obj = {
'table1': table1,
'table2': table2,
'table3': table3,
'table4': table4, 
};

This seems like such a simple task yet can't find any examples of it anywhere. Everything is always one query at a time then calling a callback function to handle the single set of results.

Any help much appreciated.

[Ivan]

Hi,

Perhaps the simplest approach to combine results from different queries is to use nested callbacks:

db.transaction(function(tx) {
    tx.executeSql("select * from table1", [],
        function(tx, rs1) {
            tx.executeSql("select * from table2", [],
                function(tx, rs2) {
                    var obj = {
                        rows1: rs1.rows,
                        rows2: rs2.rows
                    };
                });
        });
});

This works, however if you need to execute many queries, the code can quickly become cumbersome.
A better approach, which does not require such nesting of callbacks is to use jQuery Deffered Object:

db.transaction(function(tx) {
    var q1 = executeQuery(tx, "select * from table1");
    var q2 = executeQuery(tx, "select * from table2");

    $.when(q1, q2)
     .done(function(rs1, rs2) {
        var obj = {
            rows1: rs1.rows,
            rows2: rs2.rows
        };
    });
});

function executeQuery(tx, q) {
    var d = $.Deferred();

    tx.executeSql(q, [],
        function (tx, rs) {
            d.resolve(rs);
        },
        function (tx, e) {
            d.reject(e);
        });

    return d.promise();
}

Hope this helps.

Regards,
Ivan
Telerik
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