Question

我正在尝试使用函数和过程返回每个invoice_id的行数。一些invoice_id的行多于一行，我不确定执行过程时如何获取计数。例如，invoice_id（7）只有一行，而invoice_id（100）只有四行信息。

Create or replace function return_num_rows_function(invoice_id_text in varchar2)
    Return varchar2
    Is inv_id varchar2(20);
    Begin
    Select count(*)invoice_id into inv_id from invoice_line_items where invoice_id=invoice_id_text;
    Return inv_id;
    End;



 Create or replace procedure return_num_rows (invoice_id_text in varchar2)
    Is inv_id varchar(20);
    line_item_desc invoice_line_items.line_item_description%type;
    Begin
    inv_id := return_num_rows_function(invoice_id_text);
    If inv_id is not null then
    Select count(*)invoice_id, line_item_description into inv_id,line_item_desc
    From invoice_line_items where invoice_id = inv_id;
    dbms_output.put_line('The number of rows returned:'|| inv_id);
    dbms_output.put_line('Item description(s):'|| line_item_desc);
    End if;
    End;

    set serveroutput on;
    execute return_num_rows(7);

Answer 1

首先不要将字符串类型变量用于数字（invoice_id_text。
对于您的情况，最好使用过程而不是调用函数（return_num_rows_function），因为您需要两个返回参数。

没有Group By且聚集的列和非聚集的列一起使用，SQL Select语句不能使用（即不要使用此语句：

  Select count(*) invoice_id, line_item_description 
    into inv_id,line_item_desc
    From invoice_line_items 
   Where invoice_id = inv_id;

）

因此，尝试创建以下过程：

    SQL> CREATE OR REPLACE Procedure 
    return_num_rows_proc(
                         i_invoice_id        invoice_line_items.invoice_id%type,
                         inv_id          out pls_integer,
                         line_item_desc  out invoice_line_items.line_item_description%type
                        ) Is
    Begin
    for c in
     (
      Select line_item_description
        into line_item_desc
        From invoice_line_items
       Where invoice_id = i_invoice_id
     )
     loop
       line_item_desc := line_item_desc||'  '||c.line_item_description;
       inv_id := nvl(inv_id,0) + 1;
     end loop;
    End;
    /

    SQL> CREATE OR REPLACE Procedure 
       return_num_rows(
                      i_invoice_id pls_integer
                      ) Is

      inv_id         pls_integer;
      line_item_desc invoice_line_items.line_item_description%type;
    Begin
       return_num_rows_proc(i_invoice_id,inv_id,line_item_desc);
      If inv_id is not null then
        dbms_output.put_line('The number of rows returned:' || inv_id);
        dbms_output.put_line('Item description(s):' || line_item_desc);
      End if;
    End;
    /

，然后根据您的情况致电：

SQL> set serveroutput on;
SQL> execute return_num_rows(7);

Answer 2

将inv_id varchar2（20）替换为inv_id号；并且如果您想从过程中更好地获得两个输出以使用refcursor。

使用count（*）在SQL过程中获取多行

2 个答案: