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[BUG/PRB.] VFP 9.0 FIX - FIX THE CAST() FUNCTION FOR THE VFPOLEDB DRIVER
January 2024
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CCB
1. BUG:
There is a test program from Mr. Cetin Basoz:
*PROC testcastfunctionforvfpoledb
Local loCon As Adodb.Connection,;
loCmd As Adodb.Command, ;
loParm As Adodb.Parameter
loCon = Createobject('AdoDb.Connection')
loCmd = Createobject('Adodb.Command')
loCon.ConnectionString='Provider=VFPOLEDB;Data Source=test.dbc'
loCon.Open()
loCmd.ActiveConnection=loCon
loCmd.CommandText='update test set fld2 = cast(? as date) where fld1 = 0'
loParm = loCmd.CreateParameter('fld2')
loParm.Type = 129 && adChar
loParm.Direction = 1
loParm.Value = "^2018/09/22"
loParm.Size = LEN(loParm.Value)
loCmd.Parameters.Append( loParm )
loCmd.Execute()
loCon.Close
Use test
Locate for fld1 = 0
Browse
Use
RETURN
* END OF PROC TESTCASTFUNCTIONFORVFPOLEDB.
Usually, we think fld2 is always equal to DATE(2018,9,22),
But now fld2 is equal to an empty date.
2. CAUSE:
There are some BUGs for the CAST() function in the VFPOLEDB driver,
it can only convert Character data to Integer, Float, Numeric and DateTime data,
it can not convert Character data to Date data,
so fld2 is equal to an empty date.
3. RESOLUTION:
We can write some code to fix the BUG.
Label53d838 ::
mov eax , dword ptr [ Data937220 ] ;0x0053d838 : a120729300
mov dword ptr [ ebp + 0FFFFFEC4h ] , eax ;0x0053d83d : 8985c4feffff
xor eax , eax ;0x0053d843 : 33c0
inc eax ;0x0053d845 : 40
mov dword ptr [ ebp - 4 ] , eax ;0x0053d846 : 8945fc
mov dword ptr [ Data93da28 ] , eax ;0x0053d849 : a328da9300
mov eax , dword ptr [ ebp - 56 ] ;0x0053d84e : 8b45c8
mov ecx , dword ptr [eax] ;0x0053d851 : 8b08
lea edx , dword ptr [ ebp + 0FFFFFF44h ] ;0x0053d853 : 8d9544ffffff
push edx ;0x0053d859 : 52
lea edx , dword ptr [ ebp + 0FFFFFED0h ] ;0x0053d85a : 8d95d0feffff
push edx ;0x0053d860 : 52
push dword ptr [ ebp - 52 ] ;0x0053d861 : ff75cc
push dword ptr [ ebp - 92 ] ;0x0053d864 : ff75a4
pushd 03h ;0x0053d867 : 6a03
push dword ptr [ ebp - 116 ] ;0x0053d869 : ff758c
pushd offset Data9223dc ;0x0053d86c : 68dc239200
push dword ptr [ ebp + 0FFFFFF14h ] ;0x0053d871 : ffb514ffffff
push eax ;0x0053d877 : 50
call dword ptr [ ecx + 24 ] ;0x0053d878 : ff5118
mov dword ptr [ ebp - 48 ] , eax ;0x0053d87b : 8945d0
;
; -----------------------------------------------------------------------
; VFP 9.0 FIX - FIX THE CAST() FUNCTION FOR THE VFPOLEDB DRIVER
; September 2018
; -----------------------------------------------------------------------
; CCB
;
; Fix the CAST() function for the VFPOLEDB driver.
;
; 2018/9/22, by ccb
;
call vfpa_fixcastfunctionforvfpoledb
Label53d87e ::
or dword ptr [ ebp - 4 ] , 0FFFFFFFFh ;0x0053d87e : 834dfcff
mov eax , dword ptr [ ebp - 108 ] ;0x0053d882 : 8b4594
mov dword ptr [ Data93da28 ] , eax ;0x0053d885 : a328da9300
Now in VFP Advanced, the CAST() function can convert Character data to Integer, Float, Numeric, DateTime and Date data.
4. APPLIES TO:
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)
VFPOLEDB driver 9.0.0.2412
VFPOLEDB driver 9.0.0.5815
The bug has been fixed in VFP Advanced.
5. REFERENCE WEBSITES:
1, baiyujia.com:
http://www.baiyujia.com
http://www.baiyujia.com/vfpdocuments/f_vfp9fix44.asp
2, foxite.com:
https://www.foxite.com/archives/yet-another-bug-0000291461.htm
3, microsoft.com:
https://docs.microsoft.com/en-us/sql/ado/reference/ado-api/datatypeenum?view=sql-server-2017
6. OTHER:
For reference only, there is no guarantees.
Any questions or suggestions, please send me an email at ccb2000@163.com.
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