oracle OPEN FOR [USING] 语句

目的:
和ref cursor配合使用, 可以将游标变量分配给不同的SQL (而不是在declare中把游标给定死), 增加处理游标的灵活性
语法：

declare
    type type_cursor  is ref cursor [return 记录类型];  --使用 ref cursor 才能把游标分配给不同的SQL,return不能用在动态SQL中
    v_cursor type_cursor ;
begin
    OPEN v_cursor FOR select first_name, last_name from student;

    OPEN v_cursor FOR ' select first_name,last_name  from student where zip = :1 '
    USING 绑定变量1;

open	静态SQL	cursor	cursor c1 is <静态SQL文本> open c1; fetch ... into ... ; close c1;
open for	静态SQL	ref cursor	type t_1 is ref cursor; c2 t_1 ; open c2 for <静态SQL语句>;
open for using	动态SQL	type t_1 is ref cursor; c2 t_1 ; open c2 for <动态SQL语句> using ... ;

例子1:

declare
  type student_cur_type is ref CURSOR RETURN test_stu%ROWTYPE;  --声明ref cursor类型, return类型固定
    v_first_name test_stu.first_name%TYPE;
    v_last_name test_stu.last_name%TYPE;
  cur_stud student_cur_type;
begin
  open cur_stud for select first_name,last_name from student ;  --带return的ref cursor只能用在静态sql中
 loop
    fetch cur_stud into v_first_name, v_last_name;
    exit when cur_stud%NOTFOUND;
    dbms_output.put_line(v_first_name || ' ' || v_last_name);
  end loop;
  close cur_stud; 
end;

例子2:

declare
  v_zip        varchar2(5) := '&sv_zip';
  v_first_name varchar2(25);
  v_last_name  varchar2(25);
 
  type student_cur_type is ref cursor;  --声明ref cursor类型
  student_cur student_cur_type;  --student_cur是游标变量 / student_cur_type 是引用游标类型
begin
  --2打开游标变量，让它指向一个动态select查询的结果集 ; 就是使用open for语句代替一般的open语句代开游标
  open student_cur for 'select first_name,last_name ' from student where zip = :1'
    using v_zip;
  loop
    fetch student_cur into v_first_name, v_last_name;
    exit when student_cur%NOTFOUND;
    dbms_output.put_line(v_first_name || ' ' || v_last_name);
  end loop;
  close student_cur;
end;

转载自：https://blog.csdn.net/crzzyracing/article/details/75336196

来源：oschina

链接：https://my.oschina.net/u/4396523/blog/3501443

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Oracle