我为此动了脑筋。字段名称是“ ASSETID”,它可以是一个值或NULL。但实际上,该字段是文本字段(KML)。我试过了..
"ASSETID" ISNULL, "ASSETID" IS NULL, ISNULL("ASSETID"), "ASSETID" = "" NOTHING WORKED!
然而
"ASSETID" = '', "ASSETID" IN ('') did work also for search "ASSETID" in ('2251', '4321' etc)
古老但可行。