In VBA Query cannot be completed - mysql

Question

I want to find the sum of records from different tables and insert the output in a new column, when I run the code it show me the error:
"The query cannot be completed. Either the size of the query result is
larger than the maximum size of the database (2GB) or there is not enough
temporary storage space on the disk to store the query result"
And it highlight the line
STD.Open sql, cnn, adOpenStatic
My code is the following
Option Compare Database
Option Explicit
Public cnn As New ADODB.Connection
Public db As DAO.Database
Public Sub SMain()
Set db = Access.Application.CurrentDb
Set cnn = CurrentProject.Connection
Get_Value
End Sub
Private Sub Get_Value()
Dim sql As String
Dim STD As New ADODB.Recordset
Dim ODR As DAO.Recordset
Set ODR = db.OpenRecordset("Total_tbl")
Do Until ODR.EOF
DoEvents
sql = "SELECT SUM(MONT_VOL.tot_n* STD_tbl.factor_n)AS TOTAL_N FROM MONT_VOL " & _
" INNER JOIN (STD_tbl INNER JOIN Total_tbl ON STD_tbl.AREA =Total_tbl.AREA_1" & _
" AND STD_tbl.AID = Total_tbl.AID)" & _
" ON MONT_VOL.BID = STD_tbl.BLOCK" & _
" WHERE MONT_VOL.BDATE = Total_tbl.Adate" & _
" GROUP BY MONT_VOL.BID"
STD.Open sql, cnn, adOpenStatic
If STD.RecordCount <> 0 Then
ODR.Edit
ODR!New_Col= STD!TOTAL_N
ODR.Update
End If
STD.Close
ODR.MoveNext
Loop
End Sub
What mistake I did?
And am I calling the output correctly on
ODR!New_Col= STD!TOTAL_N

Answer 1

If the query is too big (which the error message indicates), then let's split it into smaller chunks. This is only properly possible in MySQL, Access doesn't support LIMIT or OFFSET, workarounds are messy, especially for totals queries
I'm making a few assumptions here:
All relevant tables are stored within the same MySQL database
Your tables have valid connection strings that can be used for ADO
Note that executing the query in MySQL alone is probably enough to fix this error.
Private Sub Get_Value()
Dim sql As String
Dim STD As New ADODB.Recordset
Dim ODR As DAO.Recordset
Set ODR = db.OpenRecordset("Total_tbl")
'Create a new ADODB connection that's directly to MySQL, and doesn't use Access
Dim adoConn2 As ADODB.Connection
adoConn2.ConnectionString = CurrentDb.TableDefs("MONT_VOL").Connect
adoConn2.Open
'Initialize variables used for pagination
Dim RecordCount As Integer
Dim PageSize As Integer
Dim Offset As Integer
Offset = 0
RecordCount = 1
PageSize = 100
Do Until ODR.EOF
DoEvents
While RecordCount <> 0
sql = "SELECT SUM(MONT_VOL.tot_n* STD_tbl.factor_n)AS TOTAL_N FROM MONT_VOL " & _
" INNER JOIN (STD_tbl INNER JOIN Total_tbl ON STD_tbl.AREA =Total_tbl.AREA_1" & _
" AND STD_tbl.AID = Total_tbl.AID)" & _
" ON MONT_VOL.BID = STD_tbl.BLOCK" & _
" WHERE MONT_VOL.BDATE = Total_tbl.Adate" & _
" GROUP BY MONT_VOL.BID" & _
" LIMIT " & Offset & "," & PageSize
STD.Open sql, adoConn2, adOpenStatic
RecordCount = STD.RecordCount
If STD.RecordCount <> 0 Then
ODR.Edit
ODR!New_Col = STD!TOTAL_N
ODR.Update
End If
STD.Close
Offset = Offset + PageSize
Wend
ODR.MoveNext
Loop
adoConn2.Close
End Sub