PRB: SET COLLATE TO Command Causes Inconsistent Comparisons

• Microsoft Visual FoxPro for Windows, versions 5.0, 5.0a, 6.0

SYMPTOMS

Comparing the equality of alphabetic characters using the UPPER() and LOWER() functions with the collation sequence set to Czech or Hungarian, produces incorrect results with some or all of the comparisons.

RESOLUTION

One workaround is to use the double equal operator (==) when making string comparisons.

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article.

MORE INFORMATION

Codepage 1250 or 852 works for a collation sequence of either Hungarian or Czech.

Steps to Reproduce Behavior

1. In the Config.fpw file, set the codepage to 1250 as follows and restart Visual FoxPro:

   Codepage=1250




2. Create a program containing the following code and run the program. This code compares the lower case letters of the alphabet:
   
   

   
      MODIFY WINDOW SCREEN FONT "Courier New",10
      CLEAR
      *SET COLLATE TO "MACHINE"
      SET COLLATE TO "CZECH" && or "Hungary" with codepage of 1250
     
      ? space(2)+"Lower to Upper"+space(14)+"Upper to Lower"+space(13) ;
        +"ASC() Values"
   
      ? space(2)+REPLICATE("-",14)+space(14)+REPLICATE("-",14)+space(13);
        +REPLICATE("-",12)
      FOR i = 1 TO 26
         DO test WITH CHR(96 + i)
      ENDFOR
   
      PROCEDURE test (s)
   
      ? s, "Lower("+s+") to Upper("+s+"):", LOWER(s) = UPPER(s), ;
        "  Upper("+s+") to Lower("+s+"):", UPPER(s) = LOWER(s),;
        ASC(s), "=", ASC(UPPER(s)), "?" 

   
   
   Comparisons using lower case letters always produce incorrect results when comparing values returned from the LOWER() to the UPPER() functions (? LOWER(s)=UPPER(s)). All of the UPPER() to LOWER() comparisons with lower case letters (? UPPER(s)=LOWER(s)) are incorrect except for the following letters:
   
   

   
   
       Letter   Decimal
       ----------------
   
       b        98
       f        102
       g        103
       h        104
       j        106
       k        107
       m        109
       p        112
       q        113
       v        118
       w        119
       x        120 

   NOTE: The lower case "g" evaluates incorrectly when comparing UPPER() to LOWER() under the Hungary collation sequence.



3. Create another program and add the following code to compare the upper case letters of the alphabet:
   
   

   
   
      MODIFY WINDOW SCREEN FONT "Courier New",10
      CLEAR
      *SET COLLATE TO "MACHINE"
      SET COLLATE TO "CZECH" && or "Hungary" with codepage of 1250
      
      ? space(2)+"Lower to Upper"+space(14)+"Upper to ;
        Lower"+space(13)+"ASC() Values"
   
      ? space(2)+REPLICATE("-",14)+space(14)+REPLICATE("-",14)+space(13);
        +REPLICATE("-",12)
      FOR i = 1 TO 26
         DO test WITH CHR(64 + i)
      ENDFOR
   
      PROCEDURE test (s)
   
      ? s, "Lower("+s+") to Upper("+s+"):", LOWER(s) = UPPER(s), ;
        "  Upper("+s+") to Lower("+s+"):", UPPER(s) = LOWER(s),;
        ASC(s), "=", ASC(UPPER(s)), "?" 

   
   
   Comparisons using upper case letters always produce incorrect results when comparing values returned from the LOWER() to the UPPER() functions (? LOWER(S)=UPPER(S)). All of the UPPER() to LOWER() comparisons with upper case letters (? UPPER(S)=LOWER(S)) are incorrect except for the following letters:
   
   

   
   
       Letter   Decimal
       ----------------
   
       B        66
       F        70
       G        71
       H        72
       J        74
       K        75
       M        77
       P        80
       Q        81
       V        86
       W        87
       X        88
    

   NOTE: The upper case "G" evaluates incorrectly when comparing UPPER() to LOWER() under the Hungary collation sequence.



4. Remove the CodePage= command from the Config.sys and change the SET COLLATE TO command to MACHINE. Now all the comparisons between UPPER() and LOWER() and LOWER() and UPPER() values are correct.

REFERENCES

For additional information, please see the following articles in the Microsoft Knowledge Base:

Q176884 PRB: Problems with SET COLLATE and Queries with Integer Fields

Q181085 SET COLLATE & Queries - Additional Problem Scenarios

Additional query words: kbVFp500a kbVFp500 kbVFp600 kbXBase KbDBFDBC kbDatabase kbdse kbcode

Keywords :
Version : WINDOWS:5.0,5.0a,6.0
Platform : WINDOWS
Issue type : kbprb