请教数据库存取简单问题！

Question

我想不重复的将字段的值取出来，用下面的代码实验adotable1.first;
while not adotable1.eof do
begin
combobox1.Items.Add(adotable1['籍贯']);
adotable1.Next ;
end;会出现重复的值。有办法吗？

Answer 1

用query,select distinct 籍贯 FROM 表

Answer 2

adotable1.sql.add(select distinct 籍贯 FROM 表);
adotable1.open;
adotable1.first;
while not adotable1.eof do
begin
combobox1.Items.Add(trim(adotable1.fields[1].asstring));
adotable1.Next ;
end;

Answer 3

procedure TFrmGuDZC.refreshcombo(combobox:tcombobox;zdm:string);
var dquery:tquery;
begin
    dquery:=tquery.Create(self);
    dquery.active:=false;
    dquery.DatabaseName := vPsDbName;
    dquery.SQL.Clear;
    dquery.SQL.add('select distinct '+zdm+' from  JG_DangA_View');
    dFbTableToCom(dquery,combobox,zdm);
    dquery.active:=false;
    dquery.Free;
    dquery:=nil;
end;
function dFbTableToCom(dbx:tdataset;combo:tcombobox;field_name,keyz:string;var zfc:array of string;addstring:string=''):boolean;overload;
var i,zs,len:integer;
begin
  len:=length(zfc);
  i:=0;
  try
    if not (dbx.active) then dbx.active:=true;
    dbx.first;
    combo.items.clear;
    if length(addstring)>0 then combo.items.add(addstring);
    while not dbx.eof do
    begin
        combo.items.add(dbx.fieldbyname(field_name).asstring);
        if i<len then zfc[i]:=dbx.fieldbyname(keyz).asstring;
        i:=i+1;
        dbx.next;
    end;
    result:=true;
  except
    result:=false;
  end;
  dbx.active:=false;
end;调用实例refreshcombo(combobox1,'籍贯');

Answer 4

'select 籍贯 from 表名 group by 籍贯

Answer 5

select distinct 籍贯 FROM 表名

Answer 6

adotable1.first;
while not adotable1.eof do
begin
combobox1.Items.Add(adotable1['籍贯']);
adotable1.Next ;
end;如果你想给拘泥的代码进行修改，那么这样做！！！
adotable1.first;
while not adotable1.eof do
begin
XXX :=adotable1['籍贯'].AsString;
If combobox1.Items.IndexOf( XXX ) = -1 Then
combobox1.Items.Add(adotable1['籍贯'].AsString);
adotable1.Next ;
end;