C++通过ADO连接ACCESS(或者SQL Server)数据库例子
#include "iostream.h"
#include "stdio.h"
#import "C:\program files\common files\system\ado\msado15.dll" no_namespace rename("EOF","adoEOF")
int main(int argc, char* argv[])
{
::CoInitialize(NULL);
_ConnectionPtr m_pConnection;
m_pConnection.CreateInstance("ADODB.Connection");
try
{
m_pConnection->Open("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Database\\mydb.mdb","","",adModeUnknown);
//m_pConnection->Open("Server=192.168.0.150,1433;uid=sa;pwd=123456;DATABASE=temp;Provider=SQLOLEDB;","","",-1);//连接SQL Server
}
catch(_com_error e)
{
cout<<"数据库连接失败，确认数据库mydb.mdb是否在当前路径下!"<<endl;
return FALSE;
}
_RecordsetPtr m_pRecordset;
m_pRecordset.CreateInstance("ADODB.Recordset");
try
{
m_pRecordset->Open("SELECT * from test",
m_pConnection.GetInterfacePtr(),
adOpenDynamic,
adLockOptimistic,
adCmdText);
}
catch(_com_error *e)
{
cout<<e->ErrorMessage()<<endl;
}
_variant_t var;
char *ID,*name;
try
{
if(!m_pRecordset->BOF)
m_pRecordset->MoveFirst();
else {
cout<<"表内数据为空"<<endl;
return 1;
}
while(!m_pRecordset->adoEOF)
{
相关文档：
Select CONVERT(varchar(100), GETDATE(), 0) as 05 16 2006 10:57AM
Select CONVERT(varchar(100), GETDATE(), 1) as 05/16/06
Select CONVERT(varchar(100), GETDATE(), 2) as 06.05.16
Select CONVERT(varchar(100), GETDATE(), 3) as 16/05/06
Select CONVERT(varchar(100), GETDATE(), 4) as 16.05.06
Select CON ......
摘自：http://www.cnblogs.com/dicky/archive/2007/01/12/618453.html
格式:
CONVERT(data_type,expression[,style])
说明:
此样式一般在时间类型(datetime,smalldatetime)与字符串类型(nchar,nvarchar,char,varchar)
相互转换的时候才用到.
例子:
SELECT CONVERT(varchar(30),getdate(),101) now
结果为 ......
TA:
1,WANG
2,ZHANG
4,LI
TB:
1,100
2,200
3,400
1.left join 左连接--以左表为基准，右表中没值的，在结果集中以null值代替。(select * from TA left join TB where TA.ID=TB.ID)
1,WANG,100
2,ZHANG,200
4,NULL
2.right join 右连接--以右表为基准，左表中没值的，在 ......
string str = System.Configuration.ConfigurationManager.AppSettings["strconn"];
string sqlpwd = "select password from bg_user where username='" + username + "'";
MySqlConnection conn = new MySqlConnection(str);
MySqlCommand cmd=new MySqlCommand(sqlpwd,conn);
MySqlDataAdapter adr = new MySqlDataA ......
常用SQL查询：
1、查看表空间的名称及大小
select t.tablespace_name, round(sum(bytes/(1024*1024)),0) ts_size
from dba_tablespaces t, dba_data_files d
where t.tablespace_name = d.tablespace_name
group by t.tablespace_name;
2、查看表空间物理文件的名称及大小
select tablespace_name, file_id, ......
