如何在 Oracle SQL Developer 中比较 INTERVAL YEAR TO MONTH 数据类型？

Question

所以我有 table Product_Information

Product	Data type
Product_ID	NUMBER(6,0)
Warranty_Period	INTERVAL YEAR(2) TO MONTH

我应该如何在音程之间进行音调检查？这是我试过的代码

case W.WARRANTY_PERIOD 
    when INTERVAL '0-0' YEAR TO MONTH THEN 'No warranty' 
    when INTERVAL '0-3' YEAR TO MONTH THEN '3 months' 
    end as Warranty 

我已经加入了 table，但我需要这样的结果：

ProductID	Warranty Left
102	1 year and 6 months
103	4 months

Answer 1

您可以使用提取函数来提取间隔期间的部分（年、月），如下所示

select PRODUCT_ID, WARRANTY_PERIOD
, case W.WARRANTY_PERIOD 
    when INTERVAL '0-0' YEAR TO MONTH THEN 'No warranty'
    else 
      case 
        when extract (year from W.WARRANTY_PERIOD) = 1 then '1 year'
        when extract (year from W.WARRANTY_PERIOD) > 1 then extract (year from W.WARRANTY_PERIOD) ||' years'
        else null
      end
  ||  case 
        when extract (year from W.WARRANTY_PERIOD) > 0 
          then
            case 
              when extract (month from W.WARRANTY_PERIOD) = 1 then ' and 1 month'
              when extract (month from W.WARRANTY_PERIOD) > 1 then ' and ' || extract (month from W.WARRANTY_PERIOD) || ' months'
              else null
            end
        else 
          case 
              when extract (month from W.WARRANTY_PERIOD) = 1 then '1 month'
              when extract (month from W.WARRANTY_PERIOD) > 1 then extract (month from W.WARRANTY_PERIOD) || ' months'
              else null
          end
        end
  end as Warranty 
from Product_Information w
;

Answer 2

您可以将正则表达式与 TO_NUMBER() 转换一起使用，例如

WITH t2 AS
(
 SELECT Warranty_Period,
        TO_NUMBER(REGEXP_SUBSTR( Warranty_Period, '[^-]+' )) AS Warranty_y,
        TO_NUMBER(REGEXP_SUBSTR( Warranty_Period, '[^-]+$')) AS Warranty_m 
   FROM t       
)
SELECT CASE Warranty_Period
         WHEN INTERVAL '0-0' YEAR TO MONTH THEN
          'No warranty'
         ELSE
          DECODE(SIGN(Warranty_y),1,NVL2(Warranty_y,Warranty_y||' year ',''))||  
          CASE WHEN Warranty_y*Warranty_m > 0 THEN 'and ' END||        
          DECODE(SIGN(Warranty_m),1,Warranty_m||' month')||
          CASE WHEN Warranty_m > 1 THEN 's' END
       END AS Warranty
  FROM t2

Demo

Answer 3

在 CASE 表达式中使用 EXTRACT：

SELECT product_id,
       CASE EXTRACT(YEAR FROM warranty_period)
       WHEN 0 THEN NULL
       WHEN 1 THEN '1 year'
       ELSE EXTRACT(YEAR FROM warranty_period) || ' years'
       END
       || CASE
       WHEN EXTRACT(YEAR FROM warranty_period) > 0
       AND  EXTRACT(MONTH FROM warranty_period) > 0
       THEN ' and '
       WHEN EXTRACT(YEAR FROM warranty_period) = 0
       AND  EXTRACT(MONTH FROM warranty_period) = 0
       THEN 'No warranty'
       END
       || CASE EXTRACT(MONTH FROM warranty_period)
       WHEN 0 THEN NULL
       WHEN 1 THEN '1 month'
       ELSE EXTRACT(MONTH FROM warranty_period) || ' months'
       END AS warranty
FROM   product_information;

其中，对于示例数据：

CREATE TABLE product_information (
  Product_ID      NUMBER(6,0),
  Warranty_Period INTERVAL YEAR(2) TO MONTH
);

INSERT INTO product_information (product_id, warranty_period)
SELECT 102, INTERVAL '1-6' YEAR TO MONTH FROM DUAL UNION ALL
SELECT 103, INTERVAL '4' MONTH FROM DUAL UNION ALL
SELECT 104, INTERVAL '0' MONTH FROM DUAL UNION ALL
SELECT 105, INTERVAL '1' MONTH FROM DUAL UNION ALL
SELECT 106, INTERVAL '1' YEAR FROM DUAL;

输出：

PRODUCT_ID	WARRANTY
102	1 year and 6 months
103	4 months
104	No warranty
105	1 month
106	1 year

db<>fiddle here