返回 select where 查询的 case 语句

Question

我对此选择查询的逻辑有问题。

SELECT

ISNULL((SELECT cs_facilities.name from cs_facilities where ci_periodicBillings.facility = cs_facilities.guid),'Unknown') as [Care Centre],

ISNULL((SELECT cs_clients.title + ' ' + cs_clients.forename + ' ' + cs_clients.surname from cs_clients where ci_periodicBillings.client = cs_clients.guid),'Unknown') as [Resident Name],

***CASE WHEN ci_periodicbillings.contributionFunder = '00000000-0000-0000-0000-000000000000' then 'No Funder' ELSE (select ci_contributionFunders.name from ci_contributionFunders where ci_contributionFunders.guid = ci_periodicBillings.contributionFunder) END as [Contribution Funder],***

ISNULL((SELECT cs_clients.ADMISSION from cs_clients where ci_periodicBillings.client = cs_clients.guid),'') as [Admission Date],

ISNULL(ci_periodicbillings.RATE,'') as [Weekly Rate],

CASE WHEN BILLRES = 1 THEN 'Self Payer' ELSE CASE WHEN BILLRES = 2 THEN 'Top up' ELSE 'Other Funder' END END as [Type of Funding],

ISNULL(ci_periodicbillings.LASTBILL,'') as [Billing Period Start Date],

ISNULL(ci_periodicbillings.NEXTBILL,'') as [Billing Period Next Repeat Date],

CASE WHEN invoiceDaysOffset = 22 then 'In Arrears' ELSE CASE WHEN invoicedaysoffset = -6 then 'In Advance' ELSE '' END END as [Advance or Arrears Billing]


from ci_periodicBillings
where facility = '00000000-0000-0000-0000-000000000000'
and ENDBILL = '1900-01-01 00:00:00.000'
order by [Care Centre], [Resident Name]

我相信您的专家会发现有问题的线是用三颗星突出显示的线。

我希望你能在这里看到我的逻辑。在 ci_periodicbillings 表中有一个标记为“contributionFunder”的列。这指的是 ci_contributionFunders 表中的一个 guid。我希望我的案例陈述说明这是否为空 guid（即 '00000000-0000-0000-0000-000000000000'）然后没有资助者，否则如果 guid 与 ci_periodicbillings 表中的列 guid 匹配，则返回 ci_contributionfunders .name 值，即资助者的名称。

谁能帮我整理一下？

Answer 1

我不知道你的错误信息是什么，我也看不出你的查询有什么实际问题，但在整理它时，我会做一些事情。

第一个是删除所有相关的子查询，并使用LEFT JOIN 代替，第二个是使用表别名而不是在整个查询中重复完整的表名。最后，我会简化 case 语句而不是嵌套它们：

SELECT  ISNULL(f.Name, 'Unknown') AS [Care Centre],
        ISNULL(c.title + ' ' + c.forename + ' ' + c.surname, 'Unknown') AS [Resident Name],
        ISNULL(cf.Name, 'No Funder') AS [Contribution Funder],
        ISNULL(c.ADMISSION, '') AS [Admission Date],
        ISNULL(pb.RATE,'') AS [Weekly Rate],
        CASE pb.BILLRES
            WHEN 1 THEN 'Self Payer' 
            WHEN 2 THEN 'Top up' 
            ELSE 'Other Funder' 
        END AS [Type of Funding],
        ISNULL(pb.LASTBILL,'') AS [Billing Period Start Date],
        ISNULL(pb.NEXTBILL,'') AS [Billing Period Next Repeat Date],
        CASE pb.invoiceDaysOffset
            WHEN 22 THEN 'In Arrears' 
            WHEN -6 THEN 'In Advance' 
            ELSE ''
        END AS [Advance or Arrears Billing]
FROM    ci_periodicBillings AS pb
        LEFT JOIN cs_facilities AS f
            ON f.guid = pb.facility
        LEFT JOIN cs_clients AS c
            ON c.guid = pb.client
        LEFT JOIN ci_contributionFunders AS cf
            ON cf.guid = pb.contributionFunder
            AND pb.contributionFunder != '00000000-0000-0000-0000-000000000000'
WHERE   pb.facility = '00000000-0000-0000-0000-000000000000'
AND     pb.ENDBILL = '1900-01-01 00:00:00.000';

我会做的最后一件事是切换到 SQL Server 允许的 Alias = <Expression> 语法，而不是 <Expression> AS Alias，因此我故意将其分开，因为它非常主观。我发现这更清晰，因为您通过扫描选择列表立即看到您正在查看的列。 Aaron Bertrand 写了一封 good article，或多或少地反映了我对这个主题的感受。

SELECT  [Care Centre] = ISNULL(f.Name, 'Unknown'),
        [Resident Name] = ISNULL(c.title + ' ' + c.forename + ' ' + c.surname, 'Unknown'),
        [Contribution Funder] = ISNULL(cf.Name, 'No Funder'),
        [Admission Date] = ISNULL(c.ADMISSION, ''),
        [Weekly Rate] = ISNULL(pb.RATE,''),
        [Type of Funding] = CASE pb.BILLRES
                                WHEN 1 THEN 'Self Payer' 
                                WHEN 2 THEN 'Top up' 
                                ELSE 'Other Funder' 
                            END,
        [Billing Period Start Date] = ISNULL(pb.LASTBILL,''),
        [Billing Period Next Repeat Date] = ISNULL(pb.NEXTBILL,''),
        [Advance or Arrears Billing] = CASE pb.invoiceDaysOffset
                                            WHEN 22 THEN 'In Arrears' 
                                            WHEN -6 THEN 'In Advance' 
                                            ELSE ''
                                        END
FROM    ci_periodicBillings AS pb
        LEFT JOIN cs_facilities AS f
            ON f.guid = pb.facility
        LEFT JOIN cs_clients AS c
            ON c.guid = pb.client
        LEFT JOIN ci_contributionFunders AS cf
            ON cf.guid = pb.contributionFunder
            AND pb.contributionFunder != '00000000-0000-0000-0000-000000000000'
WHERE   pb.facility = '00000000-0000-0000-0000-000000000000'
AND     pb.ENDBILL = '1900-01-01 00:00:00.000';

Answer 2

这是什么方言？

你使用case when ... then ... else case when ... then ...

但我知道的任何方言的正确语法是：

case when ... then ... when ... then ... else ... end

对于您的问题，我建议先离开加入，然后使用isnull 函数。

Answer 3

使用您的语法，case 语句适用于：

CASE WHEN ci_periodicbillings.contributionFunder = '00000000-0000-0000-0000-000000000000' then 'No Funder' when ci_periodicbillings.contributionFunder <> '00000000-0000-0000-0000-000000000000' THEN (select ci_contributionFunders.name from ci_contributionFunders where ci_contributionFunders.guid = ci_periodicBillings.contributionFunder) END as [Contribution Funder],