Not Exist between this date

can you share you CDT/Record structure(s)?
I think we need to see more input. in general filtering for dates is not an issue.

To query record IN a specific range, you do something like "datefield >= START AND datefield <= END". The opposite would be "datefield <= START AND datefield >= END". I think it is not the question whether Appian can do this query ....

Appian a!queryFilter() supports "BETWEEN" operator however it does not support something like NOT BETWEEN. To achieve the same you can refer to the code below.

a!queryEntity(
  entity: cons!ENT_MERCHANT,
  query: a!query(
    logicalExpression: a!queryLogicalExpression(
      operator: "AND",
      filters: {
        a!queryFilter(
          field: "transaction",
          operator: "is null"
        ),
/* Option-1  To get the data BETWEEN two dates*/
        a!queryFilter(
          field: "transactionDate",
          operator: "between",
          value: {"01/01/2022","12/31/2022"}
        ),
/* Option-2  To get the data NOT BETWEEN two dates*/
        /*a!queryFilter(*/
          /*field: "transactionDate",*/
          /*operator: "<",*/
          /*value: <STARTDATE>*/
        /*),*/
        /*a!queryFilter(*/
          /*field: "transactionDate",*/
          /*operator: ">",*/
          /*value: <ENDATE>*/
        /*)*/
      },
      ignoreFiltersWithEmptyValues: true
    ),
    pagingInfo: a!pagingInfo(
      startIndex: 1,
      batchSize: -1
    )
  )
)

Hey Stefan, I achieved it through following code, Could you please check it & tell me whether it's acceptable or not.(in place of today he can use his dates)

a!queryLogicalExpression(
operator: "AND",
filters: {

a!queryFilter(
field: "HolidayDate",
operator: "not in",
value: a!forEach(items: enumerate(1+tointeger(a!addDateTime(today(),"","",30,"","","","","")-today())),
expression: today()+fv!item)
)
},
ignoreFiltersWithEmptyValues: true
)

I think this is not a good idea. You need to compare each item in DB against a list of 31 values! This cries for bad performance.