Question

我有一个用例，我需要在where子句中编写一个包含case语句的查询，条件如下：我在“ SAMPLE_TABLE”中有名为“ BIRTHDATE”的列 1）如果仅给出日期（这是一个参数，即：from），那么我需要从SAMPLE_TABLE获取记录，该记录的BIRTHDATE> =：from 2）如果仅给出日期（这是一个参数，即：to），则获取BIRTHDATE <=：to的记录 3）如果同时给出了起始日期和截止日期，则获取这些日期之间的记录。

下面是我尝试过的查询。但是无法解决。

SELECT BIRTHDATE FROM SAMPLE_TABLE
    WHERE
    (CASE
      WHEN (:from AND NOT :to)
      THEN BIRTHDATE >= :receivefrom
      WHEN (:to AND NOT :from)
      THEN BIRTHDATE <= :to
      WHEN (:to AND :from)
      THEN BIRTHDATE BETWEEN :from AND :to
     END)

请提供一个有效的查询。预先感谢。

Answer 1

如果不包括日期，则此代码将保留空白。这已经在SQL Server中进行了测试

declare @from date='1998-12-07'
declare @to date ='2000-12-07'

SELECT [Birthdate] --when only from is available
FROM SAMPLE_TABLE
where (case when (@to='' and  @from !='') then 1 else 0  end)=1
and BIRTHDATE >= @from

UNION

SELECT [Birthdate] --when only to is available
FROM SAMPLE_TABLE
where (case when (@to!='' and  @from ='') then 1 else 0  end)=1
and BIRTHDATE <= @to

UNION

SELECT [Birthdate] --when both from and to are avilable
FROM SAMPLE_TABLE
where (case when (@to!='' and  @from !='') then 1 else 0  end)=1
and BIRTHDATE between @from and @to

或者您可以尝试

declare @from date='1998-12-07'
declare @to date ='2000-12-07'

IF (@from!='' and @to!='')

SELECT [Birthdate] 
FROM SAMPLE_TABLE
Where [Birthdate] between @from and @to 

ELSE IF (@from='' and @to!='')

(SELECT [Birthdate] 
FROM SAMPLE_TABLE
Where [Birthdate]<= @to)

ELSE IF (@from!='' and @to='')

(SELECT [Birthdate] 
FROM SAMPLE_TABLE
Where [Birthdate]>= @from)

Answer 2

我想你只是想要

SELECT BIRTHDATE
FROM SAMPLE_TABLE
WHERE (BIRTHDATE >= :from OR :from IS NULL) AND
      (BIRTHDATE <= :to OR :to IS NULL)

Answer 3

我假设如果不传递某些参数，那么它的值为NULL。

where birthdate between coalesce(:from, date('0001-01-01')) and coalesce(:to, date('9999-12-31'))

包含db2中where条件的where子句中的case

3 个答案: