Oracle 光标/引导功能

但是，在PL/SQL块中使用lead分析函数，结果不会显示。请导游

 SET SERVEROUTPUT ON
DECLARE
CURSOR C_11 IS SELECT * FROM EMP;
TYPE DD IS TABLE OF EMP%ROWTYPE;
CC DD;
TYPE RR IS  RECORD
(
ID EMP.ID%TYPE,
ENAME EMP.ENAME%type,
JOB EMP.JOB%TYPE,
HIREDATE EMP.HIREDATE%TYPE,
HIREDATE_LEAD EMP.HIREDATE%TYPE
);
HH RR;
BEGIN
OPEN C_11;
LOOP
FETCH C_11 BULK COLLECT INTO CC LIMIT 1000;
FOR I IN 1..cc.count
loop
SELECT ID,ENAME,JOB,HIREDATE, LEAD(HIREDATE) OVER(ORDER BY HIREDATE) into HH FROM EMP  where id=cc(i).id;
DBMS_OUTPUT.PUT_LINE (HH.ID ||' '||HH.ENAME||' '||HH.JOB ||' '||HH.HIREDATE||' ' || HH.HIREDATE_LEAD);
end loop;
EXIT WHEN C_11%NOTFOUND;
END LOOP; 
CLOSE C_11;
END;

处理记录和批量操作时，需要确保遵循正确的语法。请参阅下面的工作代码和内联注释：

DECLARE
  CURSOR c_11 IS SELECT * FROM emp;

  TYPE dd IS TABLE OF emp%rowtype;

  cc              dd;

  TYPE rr IS RECORD ( 
            id              emp.empno%TYPE,
            ename           emp.ename%type,
            job             emp.job%TYPE,
            hiredate        emp.hiredate%TYPE,
            hiredate_lead   emp.hiredate%TYPE
  );
  -- This is needed to be created to hold records.     
  Type v_rr is table of rr index by pls_integer;
  hh              v_rr;

BEGIN
  OPEN c_11;
  LOOP
    FETCH c_11 BULK COLLECT INTO cc LIMIT 1000;

    FOR i IN 1..cc.count 
    loop
      SELECT empno,
             ename,
             job,
             hiredate,
             nvl(LEAD(hiredate) OVER( ORDER BY hiredate) ,hiredate)
     Bulk Collect into  hh  -- Since you are using collection,you need to use BULK collect
      FROM emp;
      --where empno = cc(i).empno;  -- This looks redundant.

     -- Iterate through the loop to print the result.
      For j in 1.. hh.count
      loop
       dbms_output.put_line(hh(j).id || ' ' || hh(j).ename || ' ' || hh(j).job || ' ' || hh(j).hiredate || ' ' || hh(j).hiredate_lead);
      end loop;
    end loop;

    EXIT WHEN c_11%notfound;
  END LOOP;

  CLOSE c_11;
END;

输出：

SQL> /
7369 SMITH CLERK 17-DEC-80 20-FEB-81
7499 ALLEN SALESMAN 20-FEB-81 22-FEB-81
7521 WARD SALESMAN 22-FEB-81 02-APR-81
7566 JONES MANAGER 02-APR-81 01-MAY-81
7698 BLAKE MANAGER 01-MAY-81 09-JUN-81
7782 CLARK MANAGER 09-JUN-81 08-SEP-81
7844 TURNER SALESMAN 08-SEP-81 28-SEP-81
7654 MARTIN SALESMAN 28-SEP-81 17-NOV-81
7839 KING PRESIDENT 17-NOV-81 03-DEC-81
7900 JAMES CLERK 03-DEC-81 03-DEC-81
7902 FORD ANALYST 03-DEC-81 23-JAN-82

---

hhj.hiredate_铅的结果仍然不是there@JaspreetSingh检查您的查询，当您循环并尝试放置where子句并尝试匹配empno时，将找不到匹配的记录。如果您在其中注释empno=cci.empno；您得到的结果是，选择ID、ename、job、hiredate、LEADhiredate，通过hiredate批量从emp收集到hh，其中ID=cci.ID；但lead函数的结果仍然不存在。@Jaspreitsgh运行更新的代码。看，同样的代码也适用于我。结果就是答案。