在 SQL 服务器的 WHERE 子句中使用 DATETIME

Question

我有这个问题

SELECT  
    [MsgNumber], [StateAfter],
    DATETIMEFROMPARTS (SUBSTRING([TimeString], 7, 4), 
                       SUBSTRING([TimeString], 4, 2), 
                       SUBSTRING([TimeString], 1, 2),
                       SUBSTRING([TimeString], 12, 2), 
                       SUBSTRING([TimeString], 15, 2), 
                       SUBSTRING([TimeString], 18, 2), 0) AS dt
FROM 
    TABLE
WHERE 
    [MsgNumber] IN (5, 9, 13, 17)
ORDER BY 
    dt ASC, StateAfter ASC

输出（正常）：

+-----------+-----------+-------------------------+
| MsgNumber | tateAfter |           dt            |
+-----------+-----------+-------------------------+
|         9 |         1 | 2018-03-09 17:22:00.000 |
|         9 |         0 | 2018-03-09 17:23:37.000 |
|        17 |         1 | 2018-03-09 17:23:37.000 |
|        17 |         1 | 2018-03-09 17:29:43.000 |
|        17 |         1 | 2018-03-09 17:36:21.000 |
+-----------+-----------+-------------------------+

我想在日期上添加一个条件；为避免内部日期时间编码错误，我使用 DATETIMEFROMPARTS 函数

SELECT [MsgNumber],[StateAfter]
,DATETIMEFROMPARTS ( SUBSTRING ( [TimeString] ,7 , 4 ), SUBSTRING ( [TimeString] ,4 , 2 ), SUBSTRING ( [TimeString] ,1 , 2 ),
                    SUBSTRING ( [TimeString] ,12 , 2 ), SUBSTRING ( [TimeString] ,15 , 2 ), SUBSTRING ( [TimeString] ,18 , 2 ) , 0) as dt
FROM TABLE
WHERE [MsgNumber] IN (5,9,13,17) AND (dt > DATETIMEFROMPARTS(2018,4,9,0,0,0,0) and dt <  DATETIMEFROMPARTS(2018,5,9,0,0,0,0))
ORDER BY dt ASC,StateAfter ASC

错误：-

Messaggio 207, livello 16, stato 1, riga 5
Invalid column name 'dt'.
Messaggio 207, livello 16, stato 1, riga 5
Invalid column name 'dt'.

有人可以帮我理解为什么它不起作用吗？我也尝试了 BETWEEN 子句；谢谢

Answer 1

您不能在 where 子句中引用列别名。典型的解决方案是使用子查询或 CTE。但是 SQL 服务器有另一种我喜欢的方法，apply:

SELECT [MsgNumber], [StateAfter], v.dt
FROM TABLE t CROSS APPLY
     (VALUES (DATETIMEFROMPARTS(SUBSTRING ([TimeString], 7, 4), SUBSTRING([TimeString], 4, 2), SUBSTRING([TimeString], 1, 2),
                    SUBSTRING([TimeString], 12, 2), SUBSTRING( [TimeString], 15, 2), SUBSTRING([TimeString], 18, 2), 0)
             )
     ) V(dt)
WHERE [MsgNumber] IN (5, 9, 13, 17) AND
      v.dt > DATETIMEFROMPARTS(2018, 4, 9, 0, 0, 0, 0) AND
      v.dt <  DATETIMEFROMPARTS(2018, 5, 9, 0, 0, 0, 0))
ORDER BY dt ASC,StateAfter ASC;

我很好奇你不使用更简单的：

WHERE [MsgNumber] IN (5, 9, 13, 17) AND
      v.dt > '20180409'  AND
      v.dt < '20180509'

（我没有使用连字符，因为无论国际化设置如何，此格式将始终被解释为 YYYYMMDD。）

Answer 2

别名 dt 不能在 WHERE 子句中使用。使用像这样的子查询：

 SELECT t.[MsgNumber]
    ,t.[StateAfter]
    ,t.dt
FROM (
    SELECT [MsgNumber]
        ,[StateAfter]
        ,DATETIMEFROMPARTS(SUBSTRING([TimeString], 7, 4), SUBSTRING([TimeString], 4, 2), SUBSTRING([TimeString], 1, 2), SUBSTRING([TimeString], 12, 2), SUBSTRING([TimeString], 15, 2), SUBSTRING([TimeString], 18, 2), 0) AS dt
    FROM TABLE
    ) t
WHERE [MsgNumber] IN (
        5
        ,9
        ,13
        ,17
        )
    AND (
        dt > DATETIMEFROMPARTS(2018, 4, 9, 0, 0, 0, 0)
        AND dt < DATETIMEFROMPARTS(2018, 5, 9, 0, 0, 0, 0)
        )
ORDER BY dt ASC
    ,StateAfter ASC

Answer 3

您收到此错误是因为在您的 Table 中没有这样的列 dt。 dt 只是您在 select 中提供的别名，因此它不是列。所以你可以使用以下任何一种方法：

使用 CTE 或 SubQuery（推荐）

; with CTE
AS
(
    SELECT [MsgNumber],[StateAfter]
    ,DATETIMEFROMPARTS ( SUBSTRING ( [TimeString] ,7 , 4 ), SUBSTRING ( [TimeString] ,4 , 2 ), SUBSTRING ( [TimeString] ,1 , 2 ),

SUBSTRING ( [TimeString] ,12 , 2 ), 
SUBSTRING ( [TimeString] ,15 , 2 ), SUBSTRING ( [TimeString] ,18 , 2 ) , 0) as dt
        FROM TABLE
)
SELECT
    *
    FROM CTE
WHERE [MsgNumber] IN (5,9,13,17) 
    AND 
(
dt > DATETIMEFROMPARTS(2018,4,9,0,0,0,0) and dt <  DATETIMEFROMPARTS(2018,5,9,0,0,0,0))
    ORDER BY dt ASC,StateAfter ASC

在Where条件中给出公式（不推荐）

SELECT [MsgNumber],[StateAfter]
,DATETIMEFROMPARTS ( SUBSTRING ( [TimeString] ,7 , 4 ), SUBSTRING ( [TimeString] ,4 , 2 ), SUBSTRING ( [TimeString] ,1 , 2 ),
                    SUBSTRING ( [TimeString] ,12 , 2 ), SUBSTRING ( [TimeString] ,15 , 2 ), SUBSTRING ( [TimeString] ,18 , 2 ) , 0) as dt
FROM [TABLE]
WHERE [MsgNumber] IN (5,9,13,17) AND 
(
    DATETIMEFROMPARTS ( SUBSTRING ( [TimeString] ,7 , 4 ), SUBSTRING ( [TimeString] ,4 , 2 ), SUBSTRING ( [TimeString] ,1 , 2 ),
                    SUBSTRING ( [TimeString] ,12 , 2 ), SUBSTRING ( [TimeString] ,15 , 2 ), SUBSTRING ( [TimeString] ,18 , 2 ) , 0)
                > DATETIMEFROMPARTS(2018,4,9,0,0,0,0) 
    and 
    DATETIMEFROMPARTS ( SUBSTRING ( [TimeString] ,7 , 4 ), SUBSTRING ( [TimeString] ,4 , 2 ), SUBSTRING ( [TimeString] ,1 , 2 ),
                    SUBSTRING ( [TimeString] ,12 , 2 ), SUBSTRING ( [TimeString] ,15 , 2 ), SUBSTRING ( [TimeString] ,18 , 2 ) , 0)
                <  DATETIMEFROMPARTS(2018,5,9,0,0,0,0))
ORDER BY dt ASC,StateAfter ASC

Answer 4

发生此错误是因为 dt 不是物理列。

您可以实现如下查询：

    SELECT tbl.* FROM ( SELECT  
        [MsgNumber], [StateAfter],
        DATETIMEFROMPARTS (SUBSTRING([TimeString], 7, 4), 
                           SUBSTRING([TimeString], 4, 2), 
                           SUBSTRING([TimeString], 1, 2),
                           SUBSTRING([TimeString], 12, 2), 
                           SUBSTRING([TimeString], 15, 2), 
                           SUBSTRING([TimeString], 18, 2), 0) AS dt
    FROM 
        TABLE ) tbl
    WHERE tbl.[MsgNumber] IN (5,9,13,17) 
AND (tbl.dt > DATETIMEFROMPARTS(2018,4,9,0,0,0,0) AND tbl.dt <  DATETIMEFROMPARTS(2018,5,9,0,0,0,0)) 
    ORDER BY 
        tbl.dt ASC, tbl.StateAfter ASC

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