If you are using just the numbers 1 - 5 to represent the grade you can easily use an update Query similar to this:
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stSQL = "UPDATE [Table1] SET [Table1].[Grade] = [Grade]+1;"
currentdb.execute stSQL
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But if you are using a String Value such as 4th Graders it will need to be a little different. I recommed this approach as it will loop through the records once and make the changes you require:
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Dim stSQL as String
Dim rst as recordset
stSQL = "Select * From Table1"
Set rst = Currentdb.OpenRecordset(stSQL)
rst.moveFirst
With rst
do while Not .EOF
.Edit
Select case .Fields("Grades")
Case "5th Graders"
![Grades]= "6th Graders"
Case "4th Graders"
![Grades]= "5th Graders"
Case "3rd Graders"
![Grades]= "4th Graders"
Case "2nd Graders"
![Grades]= "3rd Graders"
Case "1st Graders"
![Grades]= "2nd Graders"
End Select
.MoveNext
loop
End with
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