How can I set the right parameters of dataset.Table[0].Compute(string expression,string filter)?
<p>I can not get the right result from the following code block:</p>

<pre><code>object ob = ds_bug.Tables[0].Compute("Count(id)",str_vertical +"= '"+"' and "+str_horizontal+" = '"+first_row.Cells[j].Text.ToString()+"'");// ds_bug has been filled some data.
</code></pre>

<p>str_vertical and str_horizontal are two  fields from the ds_bug.Tables[0], and I can see their values are right too when I  debug the code.</p>

<p>Is there any problem I set the filter with a string like " a = '##' and b = '##' "  ?</p>
