Postgresql创建游标实例

 1、创建游标测试函数

-- $$ 意思是 实际代码的开始，当遇到下一个 $$ 的时候，为代码的结属束
CREATE OR REPLACE FUNCTION CURSOR_TEST(param_gen_time VARCHAR(100)) RETURNS text AS $$
DECLARE
    titles TEXT DEFAULT '';
    record   RECORD;
    cur_records CURSOR(param_gen_time VARCHAR(100)) 
       FOR select * from t_order where gen_time<param_gen_time LIMIT 5;
BEGIN
   -- Open the cursor
   OPEN cur_records(param_gen_time);
   
   LOOP
    -- fetch row into the film
      FETCH cur_records INTO record;
    -- exit when no more row to fetch
      EXIT WHEN NOT FOUND;
 
    -- build the output
      IF COALESCE(record.store_name,'')='' THEN 
         titles := titles||','||record.order_id;
      END IF;
   END LOOP;
  
   -- Close the cursor
   CLOSE cur_records;
 
   RETURN titles;
END;
$$ LANGUAGE plpgsql;

2、调用方法

select CURSOR_TEST('2019-09-01 00:00:00');

3、执行结果