Using SQL statement for conditional update tables in access 2013 - sql

Question

I am new to databases. I am creating an Access database to track the inventory dynamics of our company. I have two tables. One is the current inventory stock, another is consumption raised by production activity. The update is done immediately after each production.
Before doing update, I want to verify the same unit is used in both stock status and consumption sheet. I try to do something like these:
Private Sub Command4_Click()
CurrentDb.Execute "SELECT o.Unit, s.Material_Unit" & _
"CASE WHEN o.Unite = s.Material_Unit" & _
"THEN UPDATE tbl_Current_Stock As o INNER JOIN bl_Temp_Raw_Material_Consumption AS s ON o.Raw_Material = s.[Ingredient/Packaging material] Set o.Stock_Level = o.Stock_Level - s.Consumption" & _
" Print'Congratulations! You have successfully updated inventory balance!'" & _
"ElSE PRINT ' Units of source data and targeted data are not matched!'" & _
"Exit Sub" & _
"End" & _
"FROM tbl_Current_Stock As o, bl_Temp_Raw_Material_Consumption AS s"
END sub
But it seems some errors exist. Please help me on these codes.
Thanks.

Answer 1

Your code is totally wrong. You can not use CASE to datermine which statement to execute, UPDATE or PRINT(PRINT is useless here, in MS Access).
You need to use either:
IF statement in your SQL query - declare o.Unite and s.Material_Unit as variables and compare them, if they match then execute update.
IF #unite = #materialunite
BEGIN
[Your Update Statement]
END
The other way:
Declare VB variables, assign the o.Unite and s.Material_Unit values to them, and write IF - ELSE statements in VB and execute your SQL queries.