sql - 在 plsql 中立即执行

Question

如何从这段代码中得到结果

EXECUTE IMMEDIATE 'SELECT * FROM ' || table_name

通过for循环

通常的方法是这样的

for items in (select * from this_table)
loop
htp.p(items.id);
end loop;

Answer 1

如果您真的需要select * from dynamic table name，那么我可能会选择dbms_sql

输入记录:

create type tq84_varchar2_tab as table of varchar2(4000);
/

输入一个结果集(它是一个记录数组):

create type tq84_varchar2_tab_tab as table of tq84_varchar2_tab;
/

执行选择并返回结果集实例的函数:

create or replace function tq84_select_star_from_table(table_name in varchar2) 
    return tq84_varchar2_tab_tab
as
    stmt_txt     varchar2(4000);
    cur          number;
    columns_desc dbms_sql.desc_tab;
    column_cnt   number;

    result_set   tq84_varchar2_tab_tab;

begin

    stmt_txt := 'select * from ' || table_name;    

    cur := dbms_sql.open_cursor;

    dbms_sql.parse(cur, stmt_txt, dbms_sql.native);
    dbms_sql.describe_columns(cur, column_cnt, columns_desc);
    dbms_sql.close_cursor(cur);


    stmt_txt := 'select tq84_varchar2_tab(';

    for i in 1 .. column_cnt loop 

        if i != 1 then
           stmt_txt := stmt_txt || ',';
        end if;

        stmt_txt := stmt_txt || columns_desc(i).col_name;

    end loop;

    stmt_txt := stmt_txt || ') from ' || table_name;

--  dbms_output.put_line(stmt_txt);

    execute immediate stmt_txt 
    bulk collect into result_set;

    return result_set;


end tq84_select_star_from_table;

然后该函数可以与类似的东西一起使用:

declare
  records   tq84_varchar2_tab_tab;
begin

  records := tq84_select_star_from_table('user_objects');

  for i in 1 .. records.count loop
      dbms_output.put_line (records(i)(5) || ': ' || records(i)(1));
  end loop;

end;
/