//Subroutine for fields to filter on 
//Creates a WHERE statement which can be used in table loads to restrict the data to a smaller set
//This WHERE statement is for loading from a QVD.  To load from SQL db change to 'WHERE IN()'

	SUB ExtendWhere(Name, ValVarName) //Name will be the filtered field name and ValVarName the values
		LET T = Name & '_COLNAME'; 
		LET ColName = $(T);
		LET Values = $(ValVarName);
	IF len(Values) > 0 THEN  
	IF len(WHERE_PART) > 0 THEN //If WHERE clause exists then extend it with further values
		LET WHERE_PART = '$(WHERE_PART) AND MATCH($(ColName),$(Values))'; 
	ELSE
		LET WHERE_PART = ' WHERE MATCH($(ColName),$(Values))'; //If WHERE clause does not exist then create it
	ENDIF
	ENDIF
	END SUB;

//Here we set the variables ready to hold the names of any fields we want considering for ODAG filtering (selection)
//The ods_ field names bind the fields to those in your Selections Application. 
//The two Sel_ variables below are examples.  Replace Customer and Sub_Group with your own fields.

	SET Sel_Customer = ; //resets the variable from any previous reload
	SET Sel_Customer = $(ods_Customer_Name); // follow 'ods_' with the field name as it appears in your UI / final load
	SET Sel_Customer_COLNAME ='CUST_NAME'; // enter the field name as it appears in the source data (e.g. QVD/SQL db)

	SET Sel_Sub_Group = ;
	SET Sel_Sub_Group = $(ods_Sub_Group_Name); 
	SET Sel_Sub_Group_COLNAME ='SUBGROUP_NAME'; 
    
	SET WHERE_PART = '';  //you may opt to add your own WHERE clause that is used in every ODAG	
    					  //e.g. you always want 2018 data... 'WHERE Year = 2018'
    					  //if so the sub routine will extend it with further selections
	
//This section builds the WHERE_PART variables that are passed to the SUB 
//It extracts the values that have been selected from each field
	FOR EACH fldname IN 'Sel_Customer', 'Sel_Sub_Group' //insert your Sel_ variables
		LET vallist = $(fldname);
	WHEN (IsNull(vallist)) LET vallist = ''; //If Qlik suggests an error here ignore it
	IF len(vallist) > 0 THEN
		CALL ExtendWhere('$(fldname)','$(vallist)');
	ENDIF
	NEXT fldname

//Evaluate the WHERE_PART variable in the script for debugging
	TRACE Generated WHERE clause: ;
	TRACE $(WHERE_PART);