SQL编程(五)

继续更新

--显示游标处理多行返回数据，隐式游标处理select into 和 dml 语句
--FETCH into
DECLARE
CURSOR emp_cursor IS
       SELECT ename,sal FROM emp WHERE deptno ='s1';
   v_ename emp.ename%TYPE;
   v_sal   emp.sal%TYPE;
BEGIN
 OPEN emp_cursor;
 LOOP
 FETCH emp_cursor INTO v_ename,v_sal;
 EXIT WHEN emp_cursor%NOTFOUND;
 dbms_output.put_line(v_ename||','||v_sal);
 END LOOP;
 CLOSE emp_cursor;
 END;
 --FETCH BULK COLLECT INTO （LIMIT）
 DECLARE
 TYPE name_array_type IS VARRAY(5) OF VARCHAR2(10);
 name_array name_array_type ;
 CURSOR emp_cursor IS SELECT ename FROM emp;
 rows INT:=5;
 v_count INT:=0;
BEGIN
OPEN emp_cursor;
LOOP
FETCH emp_cursor BULK COLLECT INTO name_array LIMIT rows;
dbms_output.put_line('雇员名');
FOR i IN 1..(emp_cursor%ROWCOUNT-v_count) LOOP
 dbms_output.put(name_array(i)||'');
 END LOOP;
 dbms_output.new_line;
 v_count:=emp_cursor%ROWCOUNT;
 EXIT WHEN emp_cursor%NOTFOUND;
 END LOOP;
 CLOSE emp_cursor;
END;
--定义记录变量提取数据
DECLARE
CURSOR emp_cursor IS
       SELECT ename,sal FROM emp;
   emp_record emp_cursor%ROWTYPE;
BEGIN
 OPEN emp_cursor;
 LOOP
 FETCH emp_cursor INTO emp_record;
 EXIT WHEN emp_cursor%NOTFOUND;
 dbms_output.put_line(emp_record.ename||','||emp_record.sal);
 END LOOP;
 CLOSE emp_cursor;
 END;
--游标定义参数 参数要在WHERE子句中
DECLARE
CURSOR emp_cursor(nos NUMBER(6)) IS
       SELECT ename,sal FROM emp WHERE deptno =nos;
   v_ename emp.ename%TYPE;
   v_sal   emp.sal%TYPE;
BEGIN
 OPEN emp_cursor(10);
 LOOP
 FETCH emp_cursor INTO v_ename,v_sal;
 EXIT WHEN emp_cursor%NOTFOUND;
 dbms_output.put_line(v_ename||','||v_sal);
 END LOOP;
 CLOSE emp_cursor;
 END;
--使用游标更新
DECLARE
 CURSOR emp_cursor IS
   SELECT ename,sal FROM emp FOR UPDATE;
   v_ename emp.ename%TYPE;
   v_oldsal emp.sal%TYPE;
 BEGIN
 OPEN emp_cursor;
 LOOP
  FETCH emp_cursor INTO v_ename,v_oldsal;
  EXIT WHEN emp_cursor%NOTFOUND;
  IF v_oldsal <2000 THEN
  UPDATE emp SET sal =sal +1000 WHERE CURRENT OF emp_cursor;
  END IF;
  END LOOP;
  CLOSE emp_cursor;
END;
DECLARE
 CURSOR emp_cursor IS
 SELECT ename,sal,dname FROM emp,dept
 WHERE emp.deptno = dept.dno;
 FOR UPDATE OF emp.deptno;--OF单个表加共享锁 NOWALT 避免等待锁
    v_ename emp.ename%TYPE;
   v_oldsal emp.sal%TYPE;
BEGIN
 OPEN emp_cursor;
 LOOP
 FETCH emp_cursor INTO v_ename,v_oldsal;
 EXIT WHEN emp_cursor%NOTFOUND;
 IF v_oldsal<2000 THEN
   UPDATE emp SET sal = sal+100 WHEN CURRENT OF emp_cursor;
    END IF;
  END LOOP;
  CLOSE emp_cursor;
 END;
--游标for循环
BEGIN
 FOR emp_record IN
 (SELECT ename FROM emp)LOOP
 dbms_output.put_line(emp_record.ename);
 END loop;
END;
--定义游标变量 return 返回
DECLARE
 TYPE emp_record_type IS RECORD(
 name VARCHAR2(10),salary NUMBER(6,2));
 TYPE emp_cursor_type IS REF CURSOR;
 RETURN emp_record_type;
 emp_cursor emp_cursor_type;
 emp_record emp_record_type;
 BEGIN
  OPEN emp_cursor FOR SELECT ename,sal FROM emp
       WHERE deptno =20;
  LOOP
  FETCH emp_cursor INTO emp_record;
  EXIT WHEN emp_cursor%NOTFOUND;
  END LOOP;
 CLOSE emp_cursor;
END: