我用以下公式实现的:if(len(SQL("HS_UAT", "SELECT distinct project_code FROM HS_UAT.dbo.Dim_import_brand where project_name='" + C4 + "' ", 1)) = 0, SQL("HS_UAT", "SELECT distinct project_code FROM HS_UAT.dbo.BI_project_dimension_tb where project_name='" + C4 + "' ", 1), SQL("HS_UAT", "SELECT distinct project_code FROM HS_UAT.dbo.Dim_import_brand where project_name='" + C4 + "' ", 1))弊端,当页面有数据时,公式失效,页面无数据时,公式生效,怎么避免此问题