示例:将游标操作模块化 (PL/SQL)

此示例演示对游标变量执行的各种操作可以如何进行模块化以形成不同的程序或 PL/SQL 组件。

以下示例演示一个过程,此过程打开一个游标变量,该游标变量的查询将检索 EMP 表中所有的行:
CREATE OR REPLACE PROCEDURE open_all_emp (
    p_emp_refcur    IN OUT SYS_REFCURSOR
)
IS
BEGIN      
    OPEN p_emp_refcur FOR SELECT empno, ename FROM emp;
END;
以下示例中的过程打开一个游标变量,该游标变量的查询将检索给定部门的所有行:
CREATE OR REPLACE PROCEDURE open_emp_by_dept (
    p_emp_refcur    IN OUT SYS_REFCURSOR,
    p_deptno        emp.deptno%TYPE
)
IS
BEGIN      
    OPEN p_emp_refcur FOR SELECT empno, ename FROM emp
        WHERE deptno = p_deptno;
END;
以下示例演示一个过程,此过程打开一个游标变量,该游标变量的查询将检索 DEPT 表中所有的行:
CREATE OR REPLACE PROCEDURE open_dept (
    p_dept_refcur    IN OUT SYS_REFCURSOR
)
IS
BEGIN      
    OPEN p_dept_refcur FOR SELECT deptno, dname FROM dept;
END;
以下示例中的过程访存并显示包含职员编号和姓名的游标变量结果集:
CREATE OR REPLACE PROCEDURE fetch_emp (
    p_emp_refcur    IN OUT SYS_REFCURSOR
)
IS
    v_empno         emp.empno%TYPE;
    v_ename         emp.ename%TYPE;
BEGIN      
    DBMS_OUTPUT.PUT_LINE('EMPNO    ENAME');
    DBMS_OUTPUT.PUT_LINE('-----    -------');
    LOOP
        FETCH p_emp_refcur INTO v_empno, v_ename;
        EXIT WHEN p_emp_refcur%NOTFOUND;
        DBMS_OUTPUT.PUT_LINE(v_empno || '     ' || v_ename);
    END LOOP;
END;
以下示例演示一个过程,此过程访存并显示包含部门编号和名称的游标变量结果集:
CREATE OR REPLACE PROCEDURE fetch_dept (
    p_dept_refcur   IN SYS_REFCURSOR
)
IS
    v_deptno        dept.deptno%TYPE;
    v_dname         dept.dname%TYPE;
BEGIN      
    DBMS_OUTPUT.PUT_LINE('DEPT   DNAME');
    DBMS_OUTPUT.PUT_LINE('----   ---------');
    LOOP
        FETCH p_dept_refcur INTO v_deptno, v_dname;
        EXIT WHEN p_dept_refcur%NOTFOUND;
        DBMS_OUTPUT.PUT_LINE(v_deptno || '     ' || v_dname);
    END LOOP;
END;
以下示例演示一个过程,此过程关闭游标变量:
CREATE OR REPLACE PROCEDURE close_refcur (
    p_refcur        IN OUT SYS_REFCURSOR
)
IS
BEGIN      
    CLOSE p_refcur;
END;
以下示例演示一个匿名块,此匿名块执行这些过程:
DECLARE
    gen_refcur      SYS_REFCURSOR;
BEGIN      
    DBMS_OUTPUT.PUT_LINE('ALL EMPLOYEES');
    open_all_emp(gen_refcur);
    fetch_emp(gen_refcur);
    DBMS_OUTPUT.PUT_LINE('****************');

    DBMS_OUTPUT.PUT_LINE('EMPLOYEES IN DEPT #10');
    open_emp_by_dept(gen_refcur, 10);
    fetch_emp(gen_refcur);
    DBMS_OUTPUT.PUT_LINE('****************');

    DBMS_OUTPUT.PUT_LINE('DEPARTMENTS');
    open_dept(gen_refcur);
    fetch_dept(gen_refcur);
    DBMS_OUTPUT.PUT_LINE('*****************');

    close_refcur(gen_refcur);
END;
执行此匿名块时,将生成以下示例输出:
ALL EMPLOYEES
EMPNO    ENAME
-----    -------
7369     SMITH
7499     ALLEN
7521     WARD
7566     JONES
7654     MARTIN
7698     BLAKE
7782     CLARK
7788     SCOTT
7839     KING
7844     TURNER
7876     ADAMS
7900     JAMES
7902     FORD
7934     MILLER
****************
EMPLOYEES IN DEPT #10
EMPNO    ENAME
-----    -------
7782     CLARK
7839     KING
7934     MILLER
****************
DEPARTMENTS
DEPT   DNAME
----   ---------
10     ACCOUNTING
20     RESEARCH
30     SALES
40     OPERATIONS
*****************