？求解精度问题：VC的float与SQL的decimal？

[bololucky]

存储过程中有一个decimal(18,0)的字段，现在要将一个vc的float的变量放进去，但是直接插入会出现精度无效的错误

_variant_t v_Score = _variant_t( Score );

pScore.CreateInstance(__uuidof(Parameter));
pScore = m_pCommand -> CreateParameter
(
_bstr_t( "Score" ),
adNumeric,
adParamInput,

v_Score
);
m_pCommand -> Parameters -> Append(pScore);
Execute的时候就弹出精度无效的错误了。。。

[bololucky]

怎么还没有人啊。。。急求答案啊！！

[jun_01]

decimal(18,0)？

用来放身份证吗？ 最好用char(18)

[jun_01]

看错了，疯，当我没说

[bololucky]

急求解答啊！高手们帮帮忙啊！！！

[bololucky]

楼上的。。。瀑布汗啊！。。。

[bololucky]

在线等待啊！各位大侠帮帮忙啊！

[jun_01]

DECIMAL FAR* pdecVal // VT_BYREF|VT_DECIMAL.

[jun_01]

Supported SQL Data Types in C and C++
Certain predefined C and C++ data types correspond to the database manager column types. Only these C/C++ data types can be declared as host variables.

The following table shows the C/C++ equivalent of each column type. When the precompiler finds a host variable declaration, it determines the appropriate SQL type value. The database manager uses this value to convert the data exchanged between the application and itself.

Note:
There is no host variable support for the DATALINK data type in any of the DB2 host languages.
Table 17. SQL Data Types Mapped to C/C++ Declarations SQL Column Type1 C/C++ Data Type SQL Column Type Description
SMALLINT
(500 or 501)
short
short int
sqlint16
16-bit signed integer
INTEGER
(496 or 497)
long
long int
sqlint322
32-bit signed integer
BIGINT
(492 or 493)
long long
long
__int64
sqlint643
64-bit signed integer
REAL4
(480 or 481)
float Single-precision floating point
DOUBLE5
(480 or 481)
double Double-precision floating point
DECIMAL(p,s)
(484 or 485)
No exact equivalent; use double Packed decimal
(Consider using the CHAR and DECIMAL functions to manipulate packed decimal fields as character data.)

[jun_01]

ANSI SQL Data Types Mapped to C++ Data Types
ANSI SQL data type C++ data type
CHAR
CString

DECIMAL
CString 1

1. ANSI DECIMAL and NUMERIC map to CString because SQL_C_CHAR is the default ODBC transfer type.

[bololucky]

lfchen的方法试过了。。。不行。。。
jun_01贴的E文勉强看懂，那一句代码看不明白怎么用。。。

[bololucky]

继续在线等！！！

[一条晚起的虫]

_variant_t var;
var.ChangeType(VT_DECIMAL);
var = a; //??

[hhcjb]

VarDecCmpR8

[hhcjb]

发错了,不好意思,VarR8FromDec

[一条晚起的虫]

decimal对应的应该是double型
var.dblVal = a;