Question

当我传递查询中所需的所有值时，返回正确的结果。但是当我只传递ID时，我得到一个空的结果集。在这种情况下是不是应该忽略类型并仍然返回正确的值？

你能帮我解决这个问题并指出问题中的问题。

SELECT 'elementary_school' AS type, elementary_school AS obj, COUNT(*) AS count
FROM data
WHERE data.report_id = ReportId         
AND (data.book_section = type 
     OR data.book_section IS NULL
     OR data.book_section = ''
    )
GROUP BY elementary_school


UNION

SELECT 'middle_school' AS type, middle_school AS obj, COUNT(*) AS count
FROM data
WHERE data.report_id = ReportId     
AND (data.book_section = type 
     OR data.book_section IS NULL
     OR data.book_section = ''
    )
 GROUP BY  middle_school


UNION

SELECT 'high_school' AS type, high_school AS obj, COUNT(*) AS count
FROM data
WHERE data.report_id = ReportId     
AND (data.book_section = type 
     OR data.book_section IS NULL
     OR data.book_section = ''
    )
GROUP BY high_school     



UNION

SELECT 'lot_sqft' AS type, lot_sqft AS obj, COUNT(*) AS count
FROM data
WHERE data.report_id = ReportId     
AND (data.book_section = type 
     OR data.book_section IS NULL
     OR data.book_section = ''
    )
GROUP BY lot_sqft       

ORDER BY count, type

Answer 1

您可以简化查询：

SELECT t.type,
        (CASE WHEN t.type = 'elementary_school' THEN elementary_school 
              WHEN t.type = 'middle_school' THEN middle_school 
              WHEN t.type = 'high_school' THEN high_school 
              WHEN t.type = 'lot_sqft' THEN lot_sqft 

         END) AS obj, COUNT(*) AS count
FROM data d CROSS JOIN
     (SELECT 'elementary_school' AS type UNION ALL
      SELECT 'middle_school' AS type UNION ALL
      SELECT 'high_school' AS type UNION ALL
      SELECT 'lot_sqft' AS type
     ) t
WHERE d.report_id = @ReportId AND
      (d.book_section = @type OR 
       d.book_section IS NULL OR
       d.book_section = ''
      )
GROUP BY t.type. obj;

我已经强调了似乎是＆＃34;参数＆＃34;使用@来阐明它们是参数而不是表格中的列。

如果要检查NULL值，请将逻辑更改为：

WHERE (d.report_id = @ReportId OR @ReportId IS NULL) AND
      (d.book_section = @type OR 
       d.book_section IS NULL OR
       d.book_section = ''
      )

Answer 2

嗯，这是一个愚蠢但诚实的错误。我能够自己解决这个问题。问题是我正在检查列是空还是空但没有检查我传递的值。所以它将如下所示：

AND (data.book_section = type 
 OR data.book_section IS NULL
 OR data.book_section = ''
)

转换为：

AND (data.book_section = type 
 OR type IS NULL
 OR type = ''
)

因为我只想检查它是否是传递param的'type'是空的还是null。无论如何，谢谢每个试图帮助的人。欢呼声。

存储过程在Optional paramaters上返回Empty结果集

2 个答案: