我怎样才能在解码功能中查询？

Question

create table ss( no number, filepath varchar2(300) )

我想在此 table

中包含 5 个或更少的 'no' 重复值

当select count(no) from ss where no=#{no} <5、insert into ss values({no},{filepath})

所以 'no' 的重复值不能超过 5。我该怎么做？

Answer 1

您可以创建一个类似的触发器来实现此逻辑：

CREATE OR REPLACE TRIGGER set_no_ss_tbl_trg
BEFORE INSERT ON ss_tbl
FOR EACH ROW
BEGIN
  DECLARE
   l_cnt_no NUMBER;
  BEGIN

    SELECT COUNT(1)
      INTO l_exceeding
      FROM g_piece
     WHERE refdoss = :new.no;
    
    IF l_cnt_no > 5 THEN 

      SELECT MIN(no)
        INTO :new.no
        FROM (SELECT COUNT(1), no 
                FROM ss_tbl
               GROUP BY no 
              HAVING COUNT(1) + 1 <= 5);      
      
    END IF;
  END;
END;

我怎样才能在解码功能中查询？

how can i put a query in decode function?

spring

oracle