What to use in Custom SQL field:
DAY(DATEADD(mm,DATEDIFF(mm, -1, [Table: Field Date]),0) -1)
Example:
where [Table: Field Date] = [Assignment: Start Date]
What to use in Custom SQL field: DAY(DATEADD(mm,DATEDIFF(mm, -1, [Table: Field Date]),0) -1) Example: where [Table: Field Date] = [Assignment: Start Date]