How to avoid that syntax : (Format(R.Date_VL,”) = Format(M.Date,”) => making macro very slow

I just realized that (Format(R.Date_VL,’yyyy/mm’) = Format(M.Date,’yyyy/mm’) is why my script is very slow.

Do you know why and if there is a way to avoid that syntax ?

its very very slow when I use format = format !!

Edit : I want to join on months and years not days

SQL = "SELECT M_Net_Flow.ID_Perf, M_Net_Flow.Net_Flow AS XX, laps"
SQL = SQL + " INTO AAA"
SQL = SQL + " FROM M_Net_Flow INNER JOIN R_Dates ON (Format(R_Dates.Date_VL,'mm/aaaa') = Format(M_Net_Flow.Date,'mm/aaaa'))"
SQL = SQL + " GROUP BY M_Net_Flow.ID_Perf, M_Net_Flow.Net_Flow, laps"
SQL = SQL + " HAVING (LAPS < " + deb + ");"
DoCmd.RunSQL SQL

Answer

You could also try using DateDiff:

SQL = "SELECT M_Net_Flow.ID_Perf, M_Net_Flow.Net_Flow AS XX, Laps "
SQL = SQL + "INTO AAA "
SQL = SQL + "FROM M_Net_Flow, R_Dates "
SQL = SQL + "WHERE DateDiff("m", R_Dates.Date_VL, M_Net_Flow.Date) = 0 "
SQL = SQL + "GROUP BY M_Net_Flow.ID_Perf, M_Net_Flow.Net_Flow, laps "
SQL = SQL + "HAVING Laps < " + deb + ";"