消息 156，级别 15，状态 1，第 7 行关键字“BETWEEN”附近的语法不正确

Question

当我运行此查询时

SELECT number, id, clientid, hash, 
    CASE WHEN expirydate IS NULL THEN 
            date 
        ELSE expirydate 
    END as date, 
    CASE company WHEN '' THEN 
            (
                SELECT CONCAT_WS(' ', firstname, lastname) 
                FROM tblcontacts 
                WHERE userid = tblclients.userid 
                and is_primary = 1
            ) 
        ELSE company END as company 

FROM "tblestimates" 
    LEFT JOIN tblclients ON tblclients.userid=tblestimates.clientid
WHERE status != 3 
AND status != 4 
AND CASE WHEN expirydate IS NULL THEN 
        (date BETWEEN '2021-06-27' AND '2021-08-08') 
    ELSE (expirydate BETWEEN '2021-06-27' AND '2021-08-08') 
    END

我遇到了这个错误：

Msg 156, Level 15, State 1, Line 7
关键字“BETWEEN”附近的语法不正确。

Answer 1

不要在where子句中使用case 。 这是不寻常和不必要的

AND 
(
      (expirydate IS NULL AND [date] BETWEEN '2021-06-27' AND '2021-08-08')
   OR expirydate BETWEEN '2021-06-27' AND '2021-08-08'
)

BTW between 是有问题的。 更好的使用（注意我的日期更改为2021-08-09 ）

AND 
(
      (expirydate IS NULL AND [date] >= '2021-06-27' AND [date] < '2021-08-09')
   OR expirydate >= '2021-06-27' AND expirydate < '2021-08-09'
)

Answer 2

CASE 语句总是解析为某个结果值，因此从逻辑上讲，这将评估为“真”或“假”：

CASE
    WHEN expirydate IS NULL THEN 
        (date BETWEEN '2021-06-27' AND '2021-08-08') 
    ELSE
        (expirydate BETWEEN '2021-06-27' AND '2021-08-08') 
END

不幸的是，SQL Server 没有布尔数据类型，因此您不能将比较的结果直接用作表达式。 相反，您需要让 CASE 语句返回支持的类型，例如 BIT：

CASE 
    WHEN expirydate IS NULL AND date BETWEEN '2021-06-27' AND '2021-08-08'
        THEN 1
    WHEN expirydate IS NOT NULL AND expirydate BETWEEN '2021-06-27' AND '2021-08-08'
        THEN 1
    ELSE 0
END

然后，您可以比较该结果以在您的 WHERE 子句中创建一个表达式：

WHERE 1 =
    CASE 
        WHEN expirydate IS NULL AND date BETWEEN '2021-06-27' AND '2021-08-08'
            THEN 1
        WHEN expirydate IS NOT NULL AND expirydate BETWEEN '2021-06-27' AND '2021-08-08'
            THEN 1
        ELSE 0
    END

但是，这种组合可以更自然地（并且可能更有效）用 OR 编写，如果将其与 AND 组合，请记住将其放在括号中：

WHERE 
  (
     expirydate IS NULL AND date BETWEEN '2021-06-27' AND '2021-08-08'
     OR
     expirydate IS NOT NULL AND expirydate BETWEEN '2021-06-27' AND '2021-08-08'
  )

在这种特殊情况下，您可以使用 COALESCE 更简单地编写它，因为您正在比较任何不为空的列：

WHERE
    COALESCE(expirydate, date) BETWEEN '2021-06-27' AND '2021-08-08'