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[转]WinCE数据库之CCeDBDatabase

时间:2021-07-01 10:21:17 帮助过:16人阅读

CCeDBDatabase类提供一系列api函数以操作WinCE下的数据库文件*.db,不过该数据库文件一般由系统自动创建于Database文件夹下面,该文件保存于内存中,仪器重启即丢失。此方式可用于数据量大且短期需要保存数据的系统。其操作具体如下所示: 1、定义数据库对象

CCeDBDatabase类提供一系列api函数以操作WinCE下的数据库文件*.db,不过该数据库文件一般由系统自动创建于Database文件夹下面,该文件保存于内存中,仪器重启即丢失。此方式可用于数据量大且短期需要保存数据的系统。其操作具体如下所示:
1、定义数据库对象:
CCeDBDatabase db;

2、创建数据库:
// Create database
CCeDBProp dbprops[3] =
{
CCeDBProp(CCeDBProp::Type_String,PROP_NO,CCeDBProp::Sort_Ascending),
CCeDBProp(CCeDBProp::Type_String,PROP_Name,CCeDBProp::Sort_Ascending),
CCeDBProp(CCeDBProp::Type_UShort,PROP_Age,CCeDBProp::Sort_Ascending)
};

if(!CCeDBDatabase::Exists(_T("Student.db")))
{
db.Create(_T("Student.db"),DB_IDENT_ID,3,dbprops);
}

3、新增记录:
UpdateData(true);

if(!db.Open(_T("Student.db")))
{
MessageBox(_T("Database open Error!"));
return;
}

CCeDBProp props[3];
CCeDBRecord rec;

props[0] = CCeDBProp((LPWSTR)(LPCTSTR)m_No,PROP_NO);
props[1] = CCeDBProp((LPWSTR)(LPCTSTR)m_Name, PROP_Name);

if(db.SeekFirstEqual(props[1]))
{
MessageBox(_T("tiger"));
db.Close();
return;
}

props[2] = CCeDBProp((USHORT)m_Age,PROP_Age);
rec.AddProps(props,3);

if(!db.AddRecord(&rec))
{
MessageBox(_T("Add Record Error!"));
return;
}

db.Close();

4、编辑记录:
UpdateData(true);

if(!db.Open(_T("Student.db")))
{
MessageBox(_T("Database open Error!"));
}

CCeDBRecord rec;
CCeDBProp pProp[2];
// pProp[0]=CCeDBProp((LPWSTR)(LPCTSTR)m_No,PROP_NO);
pProp[0]=CCeDBProp((LPWSTR)(LPCTSTR)m_Name,PROP_Name);
pProp[1]=CCeDBProp((USHORT)m_Age,PROP_Age);
rec.AddProps(pProp,2);

//OK
/* CCeDBProp pProp1[1];
pProp1[0]=CCeDBProp((LPWSTR)(LPCTSTR)m_No,PROP_NO);
db.SeekFirstEqual(pProp1[0]);

db.WriteCurrRecord(&rec);*/

//修改数据OK
//////////////////////////
/* BOOL OldSeekNext=db.m_bAutoSeekNext;
db.m_bAutoSeekNext=true;

db.SeekFirst();

CCeDBRecord temprec;
CCeDBProp* tempProp;
CString strNO,strName;

while(db.ReadCurrRecord(&temprec))
{
tempProp=temprec.GetPropFromIdent(PROP_NO);
strNO=tempProp->GetString();

tempProp=temprec.GetPropFromIdent(PROP_Name);
strName=tempProp->GetString();

if((strNO == m_No)&&(strName == m_Name))
{
if(db.m_bEOF)
db.SeekLast();
else
db.SeekPrev();

db.WriteCurrRecord(&rec);

break;
}
}

db.m_bAutoSeekNext=OldSeekNext;*/
////////////////////////

//定位记录
BOOL OldSeekNext=db.m_bAutoSeekNext;
db.m_bAutoSeekNext=true;

CCeDBProp AimProp[1];
AimProp[0]=CCeDBProp((LPWSTR)(LPCTSTR)m_No,PROP_NO);

if(db.SeekFirstEqual(AimProp[0]))
{
CCeDBRecord temprec;
CCeDBProp *tempProp;
CString strName;

// do
// {
db.ReadCurrRecord(&temprec);
// tempProp=temprec.GetPropFromIdent(PROP_Name);
// strName=tempProp->GetString();

// MessageBox(strName);

// if(!db.m_bEOF)
// MessageBox(_T("tiger"));

if(!db.m_bEOF)
db.SeekPrev();

db.DeleteCurrRecord();

/* if(strName == m_Name)
{
db.WriteCurrRecord(&rec);

break;
}*/
// }while(db.SeekNextEqual(AimProp[0]));
}
db.m_bAutoSeekNext=OldSeekNext;
/////////////////////////////////////

db.Close();

5、删除记录:
if(!db.Open(_T("Student.db")))
{
MessageBox(_T("Database open Error!"));
}

//取得列表中选择的记录
POSITION pos=m_CtrlList.GetFirstSelectedItemPosition();
int nItem=m_CtrlList.GetNextSelectedItem(pos);

CString NO=m_CtrlList.GetItemText(nItem,0);

CCeDBProp pProp[1];
pProp[0]=CCeDBProp(NO.GetBuffer(0),PROP_NO);

db.SeekFirstEqual(pProp[0]);

////////////////////
CCeDBRecord rec;
db.ReadCurrRecord(&rec);
CCeDBProp* tempProp;
tempProp=rec.GetPropFromIdent(PROP_NO);
CString strNO=tempProp->GetString();
MessageBox(strNO);
/////////////////////

db.DeleteCurrRecord();

db.Close();

6、遍历记录
m_CtrlList.DeleteAllItems();

if(!db.Open(_T("Student.db")))
{
MessageBox(_T("Database open Error!"));
}

CCeDBProp* pProp;
int nItem=0;
CString str;

BOOL bPrev = db.m_bAutoSeekNext;
db.m_bAutoSeekNext = TRUE;
db.SeekFirst();

CCeDBRecord rec;
while(db.ReadCurrRecord(&rec))
{
pProp=rec.GetPropFromIdent(PROP_NO);
LPWSTR strNO=pProp->GetString();
m_CtrlList.InsertItem(nItem,strNO);

pProp=rec.GetPropFromIdent(PROP_Name);
LPWSTR strName=pProp->GetString();
m_CtrlList.SetItemText(nItem,1,strName);

pProp=rec.GetPropFromIdent(PROP_Age);
USHORT Age=pProp->GetUShort();
str.Format(_T("%d"),Age);
m_CtrlList.SetItemText(nItem,2,str);
}

db.m_bAutoSeekNext = bPrev;

db.Close();

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