本文整理汇总了C++中CComQIPtr::GetColumnInfo方法的典型用法代码示例。如果您正苦于以下问题：C++ CComQIPtr::GetColumnInfo方法的具体用法？C++ CComQIPtr::GetColumnInfo怎么用？C++ CComQIPtr::GetColumnInfo使用的例子？那么, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类CComQIPtr的用法示例。
在下文中一共展示了CComQIPtr::GetColumnInfo方法的1个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的C++代码示例。
示例1: _BindColumns
BOOL COledbRecordset::_BindColumns()
{
_ASSERTE(m_rgBindings==NULL);
if( !IsOpen() ) return FALSE;
HRESULT Hr;
m_nCols = 0;
m_pwstrNameBuffer = NULL;
CComQIPtr<IColumnsInfo> spColInfo = m_spRowset;
if( spColInfo == NULL ) return FALSE;
DBCOLUMNINFO* rgColumnInfo = NULL;
ULONG nCols = 0;
Hr = spColInfo->GetColumnInfo(&nCols, &rgColumnInfo, &m_pwstrNameBuffer);
if( FAILED(Hr) ) return _Error(Hr);
// Allocate memory for the bindings array; there is a one-to-one
// mapping between the columns returned from GetColumnInfo() and our
// bindings.
long cbAlloc = nCols * sizeof(DBBINDING);
m_rgBindings = (DBBINDING*) ::CoTaskMemAlloc(cbAlloc);
if( m_rgBindings == NULL ) return FALSE;
::ZeroMemory(m_rgBindings, cbAlloc);
m_iAdjustIndex = 0;
// Construct the binding array element for each column.
ULONG dwOffset = 0;
for( ULONG iCol = 0; iCol < nCols; iCol++ ) {
DBBINDING& b = m_rgBindings[iCol];
b.iOrdinal = rgColumnInfo[iCol].iOrdinal;
b.dwPart = DBPART_VALUE | DBPART_LENGTH | DBPART_STATUS;
b.obStatus = dwOffset;
b.obLength = dwOffset + sizeof(DBSTATUS);
b.obValue = dwOffset + sizeof(DBSTATUS) + sizeof(ULONG);
b.dwMemOwner = DBMEMOWNER_CLIENTOWNED;
b.eParamIO = DBPARAMIO_NOTPARAM;
b.bPrecision = rgColumnInfo[iCol].bPrecision;
b.bScale = rgColumnInfo[iCol].bScale;
// Ignore bookmark column
if( (rgColumnInfo[iCol].dwFlags & DBCOLUMNFLAGS_ISBOOKMARK) != 0 ) m_iAdjustIndex++;
WORD wType = rgColumnInfo[iCol].wType;
switch( wType ) {
case DBTYPE_CY:
case DBTYPE_DECIMAL:
case DBTYPE_NUMERIC:
b.wType = DBTYPE_STR;
b.cbMaxLen = 50; // Allow 50 characters for conversion
break;
case DBTYPE_STR:
case DBTYPE_WSTR:
#ifdef _UNICODE
b.wType = DBTYPE_WSTR;
#else
b.wType = DBTYPE_STR;
#endif
b.cbMaxLen = max(min((rgColumnInfo[iCol].ulColumnSize + 1UL) * sizeof(TCHAR), 1024UL), 0UL);
break;
default:
b.wType = wType;
b.cbMaxLen = max(min(rgColumnInfo[iCol].ulColumnSize, 1024UL), 0UL);
}
// ROUNDUP on all platforms pointers must be aligned properly
#define ROUNDUP_AMOUNT 8
#define ROUNDUP_(size,amount) (((ULONG)(size)+((amount)-1))&~((amount)-1))
#define ROUNDUP(size) ROUNDUP_(size, ROUNDUP_AMOUNT)
// Update the offset past the end of this column's data
dwOffset = b.cbMaxLen + b.obValue;
dwOffset = ROUNDUP(dwOffset);
}
m_nCols = (short) nCols;
m_dwBufferSize = dwOffset;
::CoTaskMemFree(rgColumnInfo);
// Create accessor
CComQIPtr<IAccessor> spAccessor = m_spRowset;
if( spAccessor == NULL ) return FALSE;
Hr = spAccessor->CreateAccessor(DBACCESSOR_ROWDATA, m_nCols, m_rgBindings, 0, &m_hAccessor, NULL);
if( FAILED(Hr) ) return _Error(Hr);
m_pData = ::CoTaskMemAlloc(m_dwBufferSize);
if( m_pData == NULL ) return FALSE;
return TRUE;
}