使用vba在访问中向表中添加新字段

Question

I get an error in the line with the alter table command. I'm trying to create a field for each month based on the variable monthly using a loop, however it is not going through since I don't get the desired result. The code creates a column called monthly and then gives an error on the second iteration. Code is as follows:

Dim x As Integer
Dim Months As Integer
Dim monthly As String

Months = Me.YearsBack * 12

Set db = CurrentDb
If Me.Period = "monthly" Then
    For x = 1 To 2
    'Months
    monthly = "WP M" & x
    db.Execute "ALTER TABLE tblEPdata ADD COLUMN [monthly] string;"
    Next
End If

Answer 1

[monthly] is simply part of the string you are executing, it is not automatically resolved from the variable with the same name.

You need string concatenation:

Dim S As String

S = "ALTER TABLE tblEPdata ADD COLUMN [" & monthly & "] string;"
Debug.Print S
db.Execute S

Debug.Print helps with debugging, the output goes to the Immediate window (Ctrl+G).

Notice the syntax coloring in the above code.

"ALTER TABLE tblEPdata ADD COLUMN ["

is a constant string.

& concatenates strings and variables into a new string.

The [square brackets] are needed because your field names contain spaces (eg WP M2 ).