如何获得 sysref 游标选择的记录总数？

Question

背景

我正在开发一个调用 PLSQL 存储过程来检索和操作信息的 Web 应用程序。在这种情况下，数据库有两个存储过程；一个是 select 一组给定参数的记录总数，另一个是 return 具有相同参数的实际记录，加上分页参数（最小和最大行数）。

EX（不是实际代码）：

PROCEDURE get_records_count(
    p_first_name IN record_table.first_name%TYPE,
    p_last_name IN record_table.last_name%TYPE,
    p_resultCursor OUT sys_refcursor
)
IS BEGIN 
    OPEN p_resultCursor FOR 
    SELECT count(*) from record_table 
        WHERE first_name LIKE (p_first_name || '%') 
        OR last_name LIKE (p_last_name || '%');
END;


PROCEDURE get_records(
    p_first_name IN record_table.first_name%TYPE,
    p_last_name IN record_table.last_name%TYPE,
    p_min IN NUMBER,
    p_max IN NUMBER,
    p_resultCursor OUT sys_refcursor
)
IS BEGIN 
    OPEN p_resultCursor FOR 
    SELECT * from record_table 
        WHERE first_name LIKE (p_first_name || '%') 
        OR last_name LIKE (p_last_name || '%')
        AND rownum >= p_min AND rownum <= p_max;
END;

是否认为这是一个好主意超出了我的立场范围。问题是无论何时更改存储过程，结果都不匹配。短期修复是查看两个存储过程，确定哪个 selection 标准来自哪个存储过程是合适的，然后编辑另一个存储过程，以便它们都匹配。

作为长期修复，我想更改 get_records_count 过程以调用 get_records 过程，然后 return 记录总数 return 从结果 sys_refcursor 编辑。

EX:

PROCEDURE get_records_count(
    p_first_name IN record_table.first_name%TYPE,
    p_last_name IN record_table.last_name%TYPE,
    p_resultCursor OUT sys_refcursor
)
AS
v_recordsSelectedCursor sys_refcursor; 
BEGIN 
    /*I understand that I will need to change some logic in get_records to
      handle the case in which p_max is set to zero. 
      It should take this case to not apply an upper limit.*/ 
    get_records(p_first_name,p_last_name,0,0,v_recordsSelectedCursor);
    /*This is where I really have NO idea what I'm doing.
      Hopefully, you can infer what I'm trying to do. */ 
    OPEN p_resultCursor FOR
        SELECT count(*) FROM v_recordsSelectedCursor;  
END;

实际问题

如何 select return 为 sys_refcursor 编辑的记录数？结果数字需要 returned inside a sys_refcursor

Answer 1

How can I select the number of records that would be returned for a sys_refcursor? The resulting number needs to be returned inside a sys_refcursor.

您可以修改您的程序如下：

PROCEDURE get_records_count(
    p_first_name IN record_table.first_name%TYPE,
    p_last_name IN record_table.last_name%TYPE,
    p_resultCursor OUT sys_refcursor
)
AS
v_recordsSelectedCursor sys_refcursor; 
type y is table of record_table%rowtype;
z y; 
num number:=0;
BEGIN 

    get_records(p_first_name,p_last_name,0,0,v_recordsSelectedCursor);

    fetch  v_recordsSelectedCursor bulk collect into z;

    ---taking the count of refcursor
    num:=z.count;

    OPEN p_resultCursor FOR
    select num from dual;         
    dbms_output.put_line(num);

END;

查看演示：

 SQL> SELECT count(*)
     FROM emp;

     COUNT(*)
     ----------
      14

SQL> CREATE OR REPLACE PROCEDURE sys_ref_rec_cnt (var OUT sys_refcursor)
  2  AS
  3  BEGIN
  4  OPEN var FOR
  5  SELECT *
  6    FROM emp;
  7  END;
  8  /

Procedure created.    

 SQL> DECLARE
  2  x     sys_refcursor;
  3  k     sys_refcursor;
  4  TYPE y IS TABLE OF emp%ROWTYPE;
  5  z      y;
  6  num   NUMBER        := 0;
  7  BEGIN
  8  sys_ref_rec_cnt (x);
  9  
 10  FETCH x
 11  BULK COLLECT INTO z;
 12  
 13  num :=z.count;
 14  
 15  open k for
 16   select num from dual;
 17   
 18  DBMS_OUTPUT.put_line ('No. Of records-->'||num);
 19  END;
 20  /

No. Of records-->14

PL/SQL procedure successfully completed.

Answer 2

游标只是获取行的规范 - 在获取所有行之前，它不知道将返回多少行。

除非您在过程开始时使用 dbms_flashback.enable_at_time（并在结束时禁用它），否则涉及两次调用它的任何方法都有可能得到不一致的结果。当然还有性能开销。

让游标包含其总行数的唯一方法是在 select 列表中包含一个解析 count(*) over () 表达式。

如何获得 sysref 游标选择的记录总数？

How can I get the total number of records selected by a sysref cursor?

oracle

plsql

sys-refcursor

oracle-cursor