Question

I am working with MS-Access. I have a table I am modifying, the fields of the table are:

NumberOfCycles, s1,s2,s3,s4...s8

the rows have different numbers of s’s in them, some have all eight and some have less (the number of s’s is specified by NumberOfCycles). The way the table is now I have redundant data so I’ll have something like this.

NumberOfCycles, s1,s2,s3,s4...s8  
       4        1   0  1  0  
       4        0   1  0  
       4        1   0  
       4        0  

I only want the first row. I tried to solve this by adding a statement to my where clause:

where 's' + NumberOfCycles <> Null

This doesn’t work because SQL just compares the string ‘s4’ with null. How can I have it so it compares the value of the field s4 (or whatever value of NumberOfCycles) with Null?

Answer 1

Standard SQL:

WHERE
     CASE NumberOfCycles
          WHEN 1 THEN s1
          WHEN 2 THEN s2
          WHEN 3 THEN s3
          WHEN 4 THEN s4
          WHEN 5 THEN s5
          WHEN 6 THEN s6
          WHEN 7 THEN s7
          WHEN 8 THEN s8
          ELSE NULL
     END IS NOT NULL  -- Can't use <> for NULL

For MS Access I believe that this would be:

WHERE
     SWITCH(NumberOfCycles=1, s1, NumberOfCycles=2, s2, NumberOfCycles=3, s3...) IS NOT NULL