如何避免存在具有给定日期的记录的空日期记录，否则需要获取具有空日期的记录

Question

我有一张表，其中对于相同的AgencyMaster ID，我有多个条目具有不同的effectiveStart日期和effectiveEnd日期，以及一个条目，其中effectiveEnd和effectiveStart都为null。

如果我给的日期没有条目那么它应该返回记录，其中effectiveEnd和effectiveStart为null，否则对应的记录具有该特定的effectiveStart和effectiveEnd日期，但是我的问题是它的返回记录为null date并记录特定日期，总共2条记录，以便如何避免这种情况。

select AgencyBillingSettingsMaster.AgencyBillingSettingMasterID, *
from AgencyBillingSettingsMaster
where (AgencyBillingSettingsMaster.effectivePeriodStart is not null and 
       AgencyBillingSettingsMaster.effectivePeriodEnd is not null and 
       (convert(datetime,@EffectivePeriod)>=effectivePeriodStart and
        convert(datetime,@EffectivePeriod)<effectivePeriodEnd)
        or (AgencyBillingSettingsMaster.effectivePeriodStart is null and
            AgencyBillingSettingsMaster.effectivePeriodEnd is null))

附表屏幕截图

Answer 1

希望你放错了右括号。每个条件应该是分开的，但在您当前的代码中，所有条件都是单一条件。

代码将解决您的问题：

select AgencyBillingSettingsMaster.AgencyBillingSettingMasterID, *
from AgencyBillingSettingsMaster
where (AgencyBillingSettingsMaster.effectivePeriodStart is not null and 
       AgencyBillingSettingsMaster.effectivePeriodEnd is not null and 
       (convert(datetime,@EffectivePeriod)>=effectivePeriodStart and 
        convert(datetime,@EffectivePeriod)<effectivePeriodEnd)) -- here the first condition need to close
        or -- the second condition should have another block
          (AgencyBillingSettingsMaster.effectivePeriodStart is null and
           AgencyBillingSettingsMaster.effectivePeriodEnd is null)

Answer 2

在MySQL中可以将函数FOUND_ROWS()与UNION结合使用以获得条件联合：

SELECT .... FROM ... WHERE your_condition_for_existing_dates_here
UNION ALL
SELECT .... FROM ... WHERE FOUND_ROWS() = 0 AND your_condition_for_null_dates_here

您的查询将如下：

select AgencyBillingSettingsMaster.AgencyBillingSettingMasterID, *
from AgencyBillingSettingsMaster
where (AgencyBillingSettingsMaster.effectivePeriodStart is not null and 
       AgencyBillingSettingsMaster.effectivePeriodEnd is not null and 
       (convert(datetime,@EffectivePeriod)>=effectivePeriodStart and
        convert(datetime,@EffectivePeriod)<effectivePeriodEnd)
union all
select AgencyBillingSettingsMaster.AgencyBillingSettingMasterID, *
from AgencyBillingSettingsMaster
where found_rows() = 0 
        and (AgencyBillingSettingsMaster.effectivePeriodStart is null and
            AgencyBillingSettingsMaster.effectivePeriodEnd is null))