急！！请大家帮帮忙

Question

如果要查找某一字段中不重复的数据，SELECT 语句怎么写？？？

Answer 1

select distinct 字段 from table 

Answer 2

如果用一个SELECT 语句来查询多个字段
pConn->ConnectionString="Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=cailiao;Data Source=GHOST-575248EFC";
pConn->Open("","","",adConnectUnspecified);    pCmd->put_ActiveConnection(_variant_t((IDispatch*)pConn));
pCmd->CommandText="SELECT * FROM  cliao "
//问题：查询各列，分别读取不重复的数据到下面的 CComboBox中，下面就是在CComboBox中显示出不重复的数据
//就是上面的SELECT语句怎么写？？？？？
pRst=pCmd->Execute(NULL,NULL,adCmdText);
while(!pRst->rsEOF)
{
((CComboBox*)GetDlgItem(IDC_CLIAOLX))->AddString(
(_bstr_t)pRst->GetCollect("Cliaolx"));
((CComboBox*)GetDlgItem(IDC_CLIAOLX))->SetCurSel(0);     ((CComboBox*)GetDlgItem(IDC_CLIAOMC))->AddString(
(_bstr_t)pRst->GetCollect("Cliaomc"));
((CComboBox*)GetDlgItem(IDC_CLIAOMC))->SetCurSel(0);    ((CComboBox*)GetDlgItem(IDC_YD))->AddString(
(_bstr_t)pRst->GetCollect("Yd"));
((CComboBox*)GetDlgItem(IDC_YD))->SetCurSel(0); ((CComboBox*)GetDlgItem(IDC_RCL))->AddString(
(_bstr_t)pRst->GetCollect("Rcl"));
((CComboBox*)GetDlgItem(IDC_RCL))->SetCurSel(0);
((CComboBox*)GetDlgItem(IDC_ZLDJ))->AddString(
(_bstr_t)pRst->GetCollect("Zldj"));
((CComboBox*)GetDlgItem(IDC_ZLDJ))->SetCurSel(0); pRst->MoveNext();
}

Answer 3

1楼正解
 
select distinct 字段 from tablename 
or
select 字段 from tablename group by 字段
 

Answer 4

distinct 和 group by 都可以,
MS group by 的效率好像要高点～(？疑问)

Answer 5

只能一个字段一个字段distinct一下

Answer 6

还是原来的问题：
SELECT Cliaomc,Cliaolx FROM  cliao group by Cliaomc ，byCliaolx 
上面句话可以实现两个字段的查询，并且不重复
为什么我再加一个字段就不行了呢？？？前面两个字段也重复了！！奇怪！！大家帮帮忙
SELECT Cliaomc,Cliaolx,Zldj FROM  cliao group by Cliaomc，Cliaolx，Zldj