-------------------------------------------------------------------------------------------
                      [BUG/PRB.] VFP 9.0 FIX - THE QUESTION MARK SUBSTITUTION IN THE SQLEXEC() FUNCTION
                                 January 2021
                 -------------------------------------------------------------------------------------------
                                     CCB



1. BUG:

     In vfp9 (and vfp6, vfp7, vfp8), it always enables the question mark substitution in the SQLEXEC() (and SQLPREPARE()) function.

     In VFP Advanced, we can disable the question mark substitution in the SQLEXEC() (and SQLPREPARE()) function,
     for example,
     =SYS(9050,0)
     =SQLEXEC(m.q_connecthandle,"UPDATE mytable SET fld1=$Delim$?x1$Delim$ WHERE fldk1=123")
     ?x1 is a string, it will not be replaced.

     The bug only occurs on some ODBC drivers.

     The bug was reported by Simon White.


2. CAUSE:

     There are some BUGs in the following code.


3. RESOLUTION:

     We can write some code to fix the BUG.

     Fun45efd8 :: ; proc near
             mov  cl , byte ptr [eax]                                        ;0x0045efd8 :        8a08
             test cl , cl                                                    ;0x0045efda :        84c9
             je Label45f01b                                                  ;0x0045efdc :        743d
             jmp Label45eff9                                                 ;0x0045efde :        eb19

     Label45efe0 ::
             cmp  byte ptr [ eax + 1 ] , dl                                  ;0x0045efe0 :        385001
             je Label5e9a97                                                  ;0x0045efe3 :        0f84aeaa1800

     Label45efe9 ::
             cmp cl , dl                                                     ;0x0045efe9 :        3aca
             jne Label453ecd                                                 ;0x0045efeb :        0f85dc4effff

     Label45eff1 ::
             mov  cl , byte ptr [ eax + 1 ]                                  ;0x0045eff1 :        8a4801
             inc eax                                                         ;0x0045eff4 :        40
             test cl , cl                                                    ;0x0045eff5 :        84c9
             je Label45f01b                                                  ;0x0045eff7 :        7422

     Label45eff9 ::


     ;
     ;                 ---------------------------------------------------------------------------------
     ;                      VFP 9.0 FIX - THE QUESTION MARK SUBSTITUTION IN THE SQLEXEC() FUNCTION
     ;                                 January 2021
     ;                 ---------------------------------------------------------------------------------
     ;                                     CCB
     ;
     ; The question mark substitution in the SQLEXEC() function.
     ;
     ; 2021/1/28, by ccb
     ;

             cmp dword ptr vfpa_sys9050_data,00h
             jne Label45effa
             cmp dword ptr [ esp + 00h ] , offset Label8879cd ;; Fun887985 :: ; proc near
             jne Label45effa
             cmp dword ptr [ esp + 00h + (4+00h+0A8h) ] , offset Label888668 ;; Fun88835d :: ; proc near
             je Label45effe
             cmp dword ptr [ esp + 00h + (4+00h+0A8h) ] , offset Label8882de ;; Fun888261 :: ; proc near
             je Label45effe


     Label45effa ::
             cmp cl , 03Fh                                                   ;0x0045eff9 :        80f93f
             je Label45f01b                                                  ;0x0045effc :        741d

     Label45effe ::
             cmp cl , 027h                                                   ;0x0045effe :        80f927
             je Label453ea5                                                  ;0x0045f001 :        0f849e4effff
             cmp cl , 022h                                                   ;0x0045f007 :        80f922
             je Label453ea5                                                  ;0x0045f00a :        0f84954effff
             cmp cl , 05Bh                                                   ;0x0045f010 :        80f95b
             je Label5e9a90                                                  ;0x0045f013 :        0f8477aa1800
             jmp Label45eff1                                                 ;0x0045f019 :        ebd6

     Label45f01b ::
             ret                                                             ;0x0045f01b :        c3


4. APPLIES TO:

     VFP 6.0.8167.0
     VFP 6.0.8961.0 (SP5)

     VFP 7.0.0.9262
     VFP 7.0.0.9465 (SP1)

     VFP 8.0.0.2521
     VFP 8.0.0.3117 (SP1)

     VFP 9.0.0.2412
     VFP 9.0.0.3504 (SP1)
     VFP 9.0.0.4611 (SP2)
     VFP 9.0.0.5015 (SP2)
     VFP 9.0.0.5411 (SP2)
     VFP 9.0.0.5721 (SP2)
     VFP 9.0.0.5815 (SP2)
     VFP 9.0.0.6303 (SP2)
     VFP 9.0.0.6602 (SP2)
     VFP 9.0.0.7423 (SP2)

     The bug has been fixed in VFP Advanced.


5. REFERENCE WEBSITES:

     1, baiyujia.com:
     http://www.baiyujia.com
     http://www.baiyujia.com/vfpdocuments/f_vfp9fix151.asp

     2, microsoft.com:
     https://social.msdn.microsoft.com/forums/en-US/451f97f4-73c9-4239-b58e-986f735cc3a9/disable-question-mark-substitution-by-sqlexec-function


6. OTHER:

     For reference only, there is no guarantees.

     Any questions or suggestions, please send me an email at ccb2000@163.com.