Declare @sql varchar(8000)
Set @sql = 'select '
Select @sql = @sql + Subject+','
from (select distinct Subject from cj) as cj 
Set @sql=SubString(@sql,1,len(@sql)-1)
Select @sql = @sql+' from table3'
Exec (@sql)

declare 
  tsql varchar2(8000);
begin
  tsql := ' select '; 
  select (tsql || Subject || ',') into tsql from (select distinct Subject from cj) as cj;
  tsql := substr(tsql,1,Length(tsql)-1);
  tsql := tsql || ' from table3';
  execute immediate tsql;
end;

------解决方案--------------------

SQL code

declare 
  tsql varchar2(8000);
begin
  tsql := ' select '; 
  select (tsql || Subject || ',') into tsql from (select distinct Subject from cj) as cj;
  tsql := substr(tsql,1,Length(tsql)-1);
  tsql := tsql || ' from table3';
  execute immediate tsql;
end;