SQL - 如果表中存在值，如何返回 bool 值

Question

我有一堆值(地 block )，我需要检查数据库以确保它们都已经存在。有时有数百个这样的包裹。我想基本上返回一个真值或假值，这样我就可以找出哪个值不存在并解决该特定的包裹。日期方面我需要始终按前一年进行过滤。我对 SQL 很陌生，因此非常感谢您的帮助。

我已经尝试过这个:

SELECT *,
CASE WHEN EXISTS (SELECT * FROM Property WHERE taxyear = YEAR(GETDATE()) - 1 and (parcel in 
('1719309002000',
 '1024247013000',
 '1024247008000',
 '1024247001000'))
 THEN CAST(1 AS BIT) ELSE CAST(0 AS BIT) END AS ExistsStatus
 FROM Property

和

SELECT Parcel, Powner, taxyear, 
CASE WHEN taxyear = YEAR(GETDATE()) - 1 and (parcel in 
('1719309002000',
 '1024247013000',
 '1024247008000',
 '1024247001000'
)) 
THEN CAST(1 AS BIT) ELSE CAST(0 AS BIT) END AS result_field
FROM Property;

它只是遍历表中的每个地 block ，输入 0 或 1，我只想要我给出的值的结果。

Answer 1

我建议使用值表来exists。这将防止结果集中出现重复:

SELECT v.parcel,
       (CASE WHEN EXISTS (SELECT 1
                          FROM Property p
                          WHERE p.taxyear = YEAR(GETDATE()) - 1 AND
                                p.parcel = v.parcel
                         ) 
             THEN CAST(1 AS BIT) ELSE CAST(0 AS BIT)
        END) AS ExistsStatus
FROM (VALUES ('1719309002000'),
             ('1024247013000'),
             ('1024247008000'),
             ('1024247001000')
     ) v(parcel)