Hi nauna,
Hyperlink does not have serverside events. Instead use a LinkButton.
Please refer below sample.
HTML
<div>
<asp:LinkButton ID="lnkCallHyperlink" Text="Open" runat="server" OnClick="lnkCallHyperlink_Click" />
<asp:LinkButton ID="hlDetails" Text="Click" runat="server" OnClick="hlDetails_Click" />
</div>
Code
C#
protected void lnkCallHyperlink_Click(object sender, EventArgs e)
{
hlDetails_Click(null, null);
}
protected void hlDetails_Click(object sender, EventArgs e)
{
ClientScript.RegisterClientScriptBlock(this.GetType(), "", "alert('link button clicked')", true);
}
Screenshot