MS Access SQL Where Clause with LEFT function

Question

This is in MS ACCESS, I am looking to have the user enter a parameter and return values based on the left 6 characters in the user's input. I should not use the LEFT function in the where clause as it is frowned upon for processing load reasons that are beyond me. I also cannot use LIKE because the user can input any characters into the parameter. The code is:

SELECT Table1.[Customer Name], Table1.[Customer Code], Table1.[Part Number], Table1.Description, Table1.Vehicle,
       IIF ([Enter Part Number] = Table1.[Part Number], "YES, Exact Match", IIF (LEFT([Enter Part Number],6) = LEFT(Table1.[Part Number],6), "Possible Match - Base 6", "NONE")) AS Interchangeability
FROM Table1
WHERE [Customer Name] LIKE "*" & [Enter Customer Name] & "*" 
AND [Part Number] LIKE [Enter Part Number] & "*" ;

The problem is: if the user enters the full part number as the parameter, the query only returns that full part number. I am wanting to return all part numbers that have the Base-6 part number... so where the first six characters are the same. for example, the where clause I want to use is:

WHERE [Customer Name] LIKE "*" & [Enter Customer Name] & "*" 
AND LEFT([Part Number],6) = LEFT([Enter Part Number],6);

I could prompt the user to only input 6 characters, but we also need the full part number for exact match reasons. I could have them enter the base 6 and the full part number, but this is extra work and is not scalable. Please let me know if there is another way to do this or if I must use the frowned-upon LEFT function in the where clause.

Answer 1

You could combine LIKE and LEFT, where LEFT is used only on the right hand side of the Where statement and not on every record you want to check.

WHERE [Customer Name] LIKE "*" & [Enter Customer Name] & "*" 
AND [Part Number] LIKE LEFT([Enter Part Number],6) & "*" ;

Maybe you should measure that.

Be sure the user is not allowed to input wildcard characters, like * or ?.