Question

我有一个包含两个字符的表：product（varchar）和用法（varchar）。我需要以“product; usage; product; usage ...”格式将表循环到一个变量。如何才能做到这一点？以下循环不起作用：

FOR product IN (SELECT product FROM licence_check) LOOP
    product_usage :=  (licence_check.product || ';' ||  licence_check.usage);
  END LOOP;

Answer 1

它必须是一个循环吗？对于那么多的值，LISTAGG可以完成这项工作：

SQL> select listagg(dname||';'||loc, ';') within group (order by deptno) result
  2  from dept;

RESULT
--------------------------------------------------------------------------------
ACCOUNTING;NEW YORK;RESEARCH;DALLAS;SALES;CHICAGO;OPERATIONS;BOSTON

SQL>

如果必须是LOOP，我会说你错过了与PRODUCT_USAGE本身的连接。看看：

SQL> declare
  2    l_result varchar2(100);
  3  begin
  4    for cur_r in (select dname, loc from dept) loop
  5      l_result := l_result || cur_r.dname ||';'||cur_r.loc ||';';
                     -----------
                     This is what you miss
  6    end loop;
  7    dbms_output.put_line(rtrim(l_result, ';'));
  8  end;
  9  /
ACCOUNTING;NEW YORK;RESEARCH;DALLAS;SALES;CHICAGO;OPERATIONS;BOSTON

PL/SQL procedure successfully completed.

SQL>

PL / SQL循环表着色为变量

1 个答案: