I have build data table using BUILD DATA TABALE activity], and set a condition where it assign some value in BuildDataTable as row and if condition is not matched, it should assign emptyString in BuildDataTable as row.
NOTE: Please refer to picture for more clarification
You don’t need (nor want) Build Datatable here. The Read Range builds it for you. Your Build Datatable will then overwrite what Read Range did and you’ll have an empty datatable again.
I suspect what you want is Add Data Column instead of Build Data Table.
So you Read Range, then Add Data Column (and set the default value to “”) and then your loop. Only if the value matches do you then fill in the value for the column. If it doesn’t match just don’t do anything, as the column already has “” as the value.