CASE里WHERE子句

Question

我有一个查询，我需要从表中获取结果，具体取决于用户在vb.net页面上指定的参数。

声明一个变量将是理想的解决方案，但由于它是一个内联表值函数，我不能这样做，所以我已经阅读了其他问题，这在多表函数中是可能的，但是使用这种功能是不推荐的。

以下查询将是理想的解决方案或我想实现的目标。

USE [AUDIT] 
GO 

ALTER FUNCTION [dbo].[GetCreated_LPA_Audits] 
( 
@fechaInicio nvarchar (max), 
@fechaFin nvarchar (max) 
@Period int, 
@Fecha int 

) 
RETURNS TABLE 
AS 
RETURN 
(

SELECT T1.Plant,T1.Area,T1.Location,T1.IDAudit,T1.Auditor,T1.AuditDate,T1.DueDate,T1.CreationDate 
FROM Header AS T1 inner join Audits AS T2 ON T1.IDChecklist = T2.IDChecklist 
inner join AuditGroups AS T3 ON T2.IDGroup = T3.IDGroup 

    WHERE T3.IDGroup = '2' and CreationDate is not null AND 
    CASE WHEN @Periodo = '0' THEN CreationDate>= @fechaInicio 
     WHEN @Periodo = '1' THEN DATEPART(MONTH,CreationDate)>= @Fecha 
     WHEN @Periodo = '2' THEN 
           CASE WHEN @Fecha = 13 THEN 
                DATEPART(MONTH,CreationDate)>= 1 
           END 
     WHEN @Periodo = '2' THEN 
           CASE WHEN @Fecha = 14 THEN 
                DATEPART(MONTH,CreationDate)>= 7 
           END 
     WHEN @Periodo = '3' THEN 
           CASE WHEN @Fecha = 15 THEN 
                DATEPART(Year,CreationDate)>= 2015 
           END 
    END 
    AND 

CASE WHEN @Periodo = '0' THEN @fechaInicio<=CreationDate 
    WHEN @Periodo = '1' THEN @Fecha<=DATEPART(MONTH,CreationDate) 
    WHEN @Periodo = '2' THEN 
           CASE WHEN @Fecha = 13 THEN 
                6<=DATEPART(MONTH,CreationDate) 
           END 
     WHEN @Periodo = '2' THEN 
           CASE WHEN @Fecha = 14 THEN 
                12<=DATEPART(MONTH,CreationDate) 
           END 
     WHEN @Periodo = '3' THEN 
           CASE WHEN @Fecha = 15 THEN 
                DATEPART(Year,CreationDate)>= 2015 
           END 
    END 

AND 在先前的查询@fechaInicio，@fechaFin，@Periodo和@Fecha是由用户提供的参数。

基本上如果@Periodo = 0我需要得到结果，其中 CreationDate>= @fechaInicio and CreationDate<=@fechaFin

如果@Periodo = 1我需要在那里 DATEPART(MONTH,CreationDate)>= @Fecha and DATEPART(MONTH,CreationDate)<= @Fecha

等等的结果。 希望我明确表示感谢！

编辑利用@MatBailie伪代码，有些轻视的改变和回答他的问题

IF @periodo = '0' THEN 
    WHERE CreationDate >= @fechaInicio -- Copied from 1st CASE 
     AND @fechaFin <= CreationDate -- Copied from 2nd CASE 

    -- gets results from @fechaInicio to @fechaFin 
    -- i.e. results from 04/05/2016 to 04/16/2016 

IF @periodo = '1' THEN 
    WHERE DATEPART(MONTH,CreationDate) >= @Fecha -- Copied from 1st CASE 
     AND @Fecha <= DATEPART(MONTH,CreationDate) -- Copied from 2nd CASE 

    -- In these case both conditions are the same 'cause 
    -- @Fecha is the number of a month (1 - 12) 
    -- i.e. @Fecha = 3 will get all the results of March 
    -- regardless of what it is on @fechaInicio and @fechaFin 

IF @periodo = '2' THEN 
    IF @fetcha = 13 THEN 
     WHERE DATEPART(MONTH,CreationDate)>= 1 -- Copied from 1st CASE 
      AND 6<=DATEPART(MONTH,CreationDate) -- Copied from 2nd CASE 
    IF @fetcha = 14 THEN 
     WHERE DATEPART(MONTH,CreationDate)>= 7 -- Copied from 1st CASE 
      AND 12<=DATEPART(MONTH,CreationDate) -- Copied from 2nd CASE 

    -- You never use @fetchaInicio? 
    -- You want everything in the first 6 months or last 6 months 
    -- For every year 
    -- Regardless of what is in @fetchaInicio? 

    -- Exactly!!-- 

IF @periodo = '3' THEN 
    IF @fetcha = 15 THEN 
     WHERE DATEPART(Year,CreationDate)>= 2015 -- Copied from 1st CASE 
      AND 2015 <= DATEPART(Year,CreationDate) -- Copied from 2nd CASE 

    -- 

又是怎么回事的情况下@periodo = '2' AND @fetcha NOT IN (13,14)？ 那么情况如何@periodo = '3' AND @fetcha NOT IN (15)？

这种情况将不存在，其限制在客户端。 如果他们选择@Periodo = '2'那么@Fecha将具有1-12的值，而没有其他值。

同样的，@Periodo = '3'的15或再@Fecha将有值16，既指的2015年或2016年

Answer 1

首先，你是正确的，内联TFV真的更快。如果不是过度复杂。 我最好为SQL Server端的每个@Periodo参数值设置一些iTFV，并在客户端选择正确的代码。

或者你可以做一个单一的iTVF

WHERE 
    @Periodo = '0' AND CreationDate>= @fechaInicio and CreationDate<=@fechaFin 
    OR @Periodo = '1' and DATEPART(MONTH,CreationDate)>= @Fecha and DATEPART(MONTH,CreationDate)<= @Fecha 
    ... 

但MS SQL众所周知，建立ocassionally不良计划或运营商可以使您的努力，坚持iTVF没用。

Answer 2

每当你要使用的参数如条件的WHERE子句中，你可以按照以下格式：

WHERE 
((@Periodo = '0' AND CreationDate 
OR (@Periodo = '1' AND @VPeriodo = CAST(DATEPART(MONTH,CreationDate) as Nvarchar(10)) 
OR (@Periodo = '2' AND @VPeriodo = CAST(DATEPART(MONTH,CreationDate) as Nvarchar(10)) 
OR (@Periodo = '3' AND @VPeriodo = CAST(DATEPART(Year,CreationDate) as Nvarchar(10))) 

请确保参数评估是第一次，因为它会很快并且为假将停止查询继续处理更多的处理密集部分条件。

Answer 3

重新组织WHERE子句会使得过滤的字段位于左侧，而不在任何函数内。

例如...

WHERE 
     CreationDate >= @VPeriodo 
    AND CreationDate < CASE 
         WHEN @Periodo = '0' THEN DATEADD(DAY, 1, @VPeriodo) 
         WHEN @Periodo = '1' THEN DATEADD(MONTH, 1, @VPeriodo) 
         WHEN @Periodo = '2' THEN DATEADD(MONTH, 1, @VPeriodo) 
         WHEN @Periodo = '3' THEN DATEADD(YEAR, 1, @VPeriodo) 
         END 

在这个例子中，右手边是所有标量常量。这意味着您可以在CreationDate字段上进行范围扫描。

此外，@VPeriodo应该是DATE或DATETIME而不是VARCHAR(MAX)。

编辑：包箍为使用VARCHAR处理

所有日期的需要使用VARCHAR时要在格式YYYYMMDD通过跳跃。这是为了让stirngs的natrual顺序相同日期的自然顺序...
- '20161101'>'20161002'

当使用其他格式，如YYYYDDMM，失败...
- '20160111' < '20160210'问题，这种格式的10月2日来到后11月1日

WHERE 
     CreationDate >= @VPeriodo 
    AND CreationDate < CONVERT(
         NVARCHAR(8), 
         CASE 
          WHEN @Periodo = '0' THEN DATEADD(DAY, 1, CAST(@VPeriodo AS DATE)) 
          WHEN @Periodo = '1' THEN DATEADD(MONTH, 1, CAST(@VPeriodo AS DATE)) 
          WHEN @Periodo = '2' THEN DATEADD(MONTH, 1, CAST(@VPeriodo AS DATE)) 
          WHEN @Periodo = '3' THEN DATEADD(YEAR, 1, CAST(@VPeriodo AS DATE)) 
         END, 
         112 -- Format code for ISO dates, YYYYMMDD 
        ) 

编辑：后的OP提出了意见和修改的问题

这里OP一个问题，所有我做的是重新安排你的代码，使伪代码你已经什么书面...

IF @periodo = '0' THEN 
    WHERE CreationDate >= @fetchaInicio -- Copied from 1st CASE 
     AND @fetchaInicio <= CreationDate -- Copied from 2nd CASE 

    -- These two conditions are direct from your code 
    -- But they're the same as each other 
    -- What do you REALLY want to happen when @Periodo = '0'? 

IF @periodo = '1' THEN 
    WHERE DATEPART(MONTH,CreationDate) >= @Fecha -- Copied from 1st CASE 
     AND @Fecha <= DATEPART(MONTH,CreationDate) -- Copied from 2nd CASE 

    -- These two conditions are direct from your code 
    -- But they're the same as each other 
    -- What do you REALLY want to happen when @Periodo = '1'? 

IF @periodo = '2' THEN 
    IF @fetcha = 13 THEN 
     WHERE DATEPART(MONTH,CreationDate)>= 1 -- Copied from 1st CASE 
      AND 6<=DATEPART(MONTH,CreationDate) -- Copied from 2nd CASE 
    IF @fetcha = 14 THEN 
     WHERE DATEPART(MONTH,CreationDate)>= 7 -- Copied from 1st CASE 
      AND 12<=DATEPART(MONTH,CreationDate) -- Copied from 2nd CASE 

    -- You never use @fetchaInicio? 
    -- You want everything in the first 6 months or last 6 months 
    -- For every year 
    -- Regardless of what is in @fetchaInicio? 

IF @periodo = '3' THEN 
    IF @fetcha = 15 THEN 
     WHERE DATEPART(Year,CreationDate)>= 2015 -- Copied from 1st CASE 
      AND DATEPART(Year,CreationDate)>= 2015 -- Copied from 2nd CASE 

    -- Both conditions are the same again, why? 
    -- You want everything from 2015 onwards, forever? 
    -- You never use @fetchaInicio? 
    -- It's always 2015? 

那么情况如何@periodo = '2' AND @fetcha NOT IN (13,14)？ 那么情况如何@periodo = '3' AND @fetcha NOT IN (15)？

请你能陪我上面的伪代码，并给什么你真的想在每种情况下做一些实际的例子吗？