title: Check if exist data in table angular
body: <p>I have this function :</p>
  <pre><code>  onSubmit() {
       this.http.getDataFromServer('api/all').subscribe(resp =&gt; {
         console.log(resp.data)
      })
  
      this.http.postDataToServer('api/in', this.companyForm.value).subscribe(() =&gt; {
        //show that organization is added in dialog
        this.dialog.open(DisplayPopupComponent, {
          data: {
            title: &quot;Organization Updated Successfully!&quot;
          }
        });
      })
    }
  </code></pre>
  <p>We have data in <code>resp.data</code>, i want use this data out of this query to check if equal NULL or not to implement second query.</p>
  <p>Graph :</p>
  <p>resp.data -----&gt; exist data? then apply second query (api/in).</p>
  <pre><code>      -----&gt; NULL data do nothing.
  </code></pre>