用ado读sql2000 sever中数据时float全读为0，但bstr正确，为什么？请帮助！

[lbsylh]

用ado读sql2000 sever中数据时float全读为0，但bstr正确，为什么？请帮助！

float ff=pFeild->GetItem("someItem")->value.fltVal; //ff=0???
_bstr_t bb=pFeild->GetItem("someItem")->value.bstrVal; //bb="some text"

[RodgerLiang]

You must make sure the return value's type is float.
You can check pFeild->GetItem("someItem")->value.vt

MSDN:
typedef struct tagVARIANT {
VARTYPE vt;
unsigned short wReserved1;
unsigned short wReserved2;
unsigned short wReserved3;
union {
unsigned char bVal; // VT_UI1.
short iVal; // VT_I2 .
long lVal; // VT_I4 .
float fltVal; // VT_R4 .
double dblVal; // VT_R8 .
VARIANT_BOOL boolVal; // VT_BOOL.
SCODE scode; // VT_ERROR.
CY cyVal; // VT_CY .
DATE date; // VT_DATE.
BSTR bstrVal; // VT_BSTR.
IUnknown FAR* punkVal; // VT_UNKNOWN.
IDispatch FAR* pdispVal; // VT_DISPATCH.
SAFEARRAY FAR* parray; // VT_ARRAY|*.
unsigned char FAR* pbVal; // VT_BYREF|VT_UI1.
short FAR* piVal; // VT_BYREF|VT_I2.
long FAR* plVal; // VT_BYREF|VT_I4.
float FAR* pfltVal; // VT_BYREF|VT_R4.
double FAR* pdblVal; // VT_BYREF|VT_R8.
VARIANT_BOOL FAR* pboolVal; // VT_BYREF|VT_BOOL.
SCODE FAR* pscode; // VT_BYREF|VT_ERROR.
CY FAR* pcyVal; // VT_BYREF|VT_CY.
DATE FAR* pdate; // VT_BYREF|VT_DATE.
BSTR FAR* pbstrVal; // VT_BYREF|VT_BSTR.
IUnknown FAR* FAR* ppunkVal; // VT_BYREF|VT_UNKNOWN.
IDispatch FAR* FAR* ppdispVal; // VT_BYREF|VT_DISPATCH.
SAFEARRAY FAR* FAR* pparray; // VT_ARRAY|*.
VARIANT FAR* pvarVal; // VT_BYREF|VT_VARIANT.
void FAR* byref; // Generic ByRef.
};

[greenery]

试试
_variant_t vvt=pFeild->GetItem("someItem");
float f = float(vvt);

[dyw]

试试先变更类型，再读。
var.ChangeType(...);

[RodgerLiang]

You make a mistake :

the variant value should be
_variant_t vvt=pFeild->GetItem("someItem")->Value;

you shouldn't use value.fltVal, Because vt = VT_DECIMAL
you can try this :
float ff = pFeild->GetItem("someItem")->value;

[lbsylh]

to rodgerliang

原为float ff=pFeild->GetItem("someItem")->value.fltVal; //ff=0???
改为_variant_t vvt=pFeild->GetItem("someItem");
结果vvt为VT_BOOL型
why???
sql2000 server里面该变量设为decimal

请帮忙!!!!!!!!!!!!!

[knightsj]

我看应该这样

variant vVal;//用variant类型可以转换成其它数据类型
_bstr_t bstrVal;
vVal = pFeild->GetItem("someItem")->value;
bstrVal = vVal.bstr;

[lbsylh]

to knightsj

对不起，你可能误会我的问题了。
我的问题是读bstr类型数据没问题，date类型数据也没问题
但decimal(sql2000),float(vc)出现问题！！！
读出来的float数全为0，检查发现读出的竟是BOOL类型！！！

请帮助。

[lbsylh]

to RodgerLiang greenery knightsj

THANKS!!!

float ff = pFeild->GetItem("someItem")->value;

this is right!