Using Alasql can you replace null column with empty string
<p>In my angular controller i have ExportToExcel function, which is using alasql to export data to Excel and the data is coming from angular array. 
<strong>The issue is the array might contains null as data, is it a way to replace null to empty string in alasql</strong> </p>

<p>Following is the function</p>

<pre><code> ac.ExportToExcel = function () {
        var time = new Date().toJSON().slice(0, 10);
        alasql('SELECT * INTO XLSX("ExchangeReport' + time + '.xlsx",{headers:true}) FROM ? WHERE BillingPeriod = "' + ac.ExchangeReport.BillingPeriod + '" or "' + ac.ExchangeReport.BillingPeriod + '" = "" ', [ac.ExchangeDatas]);
    }
</code></pre>

<p>And this is my data source</p>

<pre><code>ac.ExchangeDatas = [];
</code></pre>

<p>from</p>

<pre><code>        ac.GetAllExchangeData = function () {
        AccountRepository.GetAllExchangeData().$promise.then(
            function (data) {
                ac.ExchangeDatas = data.result;
            },
            function (err) {
                console.log("error in GetAllExchangeData : " + err);
            }
        );
    }
</code></pre>

<p>Data in excel:</p>

<p><a href="https://i.stack.imgur.com/dzipM.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/dzipM.png" alt="enter image description here"></a></p>