1.用copyfile
The CopyFile function copies an existing file to a new file.
BOOL CopyFile(
LPCTSTR lpExistingFileName, // pointer to name of an existing file
LPCTSTR lpNewFileName, // pointer to filename to copy to
BOOL bFailIfExists // flag for operation if file exists
);
Parameters
lpExistingFileName
Points to a null-terminated string that specifies the name of an existing file.
lpNewFileName
Points to a null-terminated string that specifies the name of the new file.
bFailIfExists
Specifies how this operation is to proceed if a file of the same name as that specified by lpNewFileName already exists. If this parameter is TRUE and the new file already exists, the function fails. If this parameter is FALSE and the new file already exists, the function overwrites the existing file and succeeds.
Return Values
If the function succeeds, the return value is nonzero.
If the function fails, the return value is zero. To get extended error information, call GetLastError.
Remarks
Security attributes for the existing file are not copied to the new file.
File attributes (FILE_ATTRIBUTE_*) for the existing file are copied to the new file. For example, if an existing file has the FILE_ATTRIBUTE_READONLY file attribute, a copy created through a call to CopyFile will also have the FILE_ATTRIBUTE_READONLY file attribute. For further information on file attributes, see CreateFile.
2.var dToday:TDate;
sBeforeYesterday:string;
begin
dToday:=Date;
sBeforeYesterday:=FormatDateTime('yyyy-mm-dd',dToday-2);
qry.sql.clear;
qry.sql.add('delete from youtable where days<'+''''+sBeforeYesterday+'''');
qry.ExcSQL;
end;
就可删除.若为日期型.就要根据你的数据库里用什么函数了.db我不熟悉,例如ORACLE;
qry.sql.add('delete from youtable where days<to_date(''yyyy-mm-dd'','+''''+sBeforeYesterday+'''');
