分配空值复制匹配行的查询

我有以下查询，

select v.pattern_id,v.id,v.pdb_id as viocardId,p.pdb_id as PID,s.vio_id as SiVioId, r.date as orcdate, s.created_date as sivcreateddate 
from orc_orcviolation v, orc_orcpattern p, siverify_siverifyverificationsite s, orc_orccheck o, orc_orcrecord r 
where v.pattern_id = p.id 
and p.pdb_id = s.pattern_id 
and p.if_target = s.if_target 
and p.if_secure <> 1 
and v.check_id = o.id 
and o.record_id = r.id

我得到了上面的查询结果如下，

pattern_id id viocardId PID SiVioId orcdate sivcreateddate 
469064 1205777 3024788 2335310 1739560 2014-05-02 16:14:32 2015-06-21 13:18:49 
469064 1241653 3097963 2335310 1739560 2014-05-24 17:07:55 2015-06-21 13:18:49 
469064 1309143 3393980 2335310 1739560 2014-07-19 17:49:11 2015-06-21 13:18:49 
469064 1514825 4079963 2335310 1739560 2014-10-29 14:07:58 2015-06-21 13:18:49 
469064 1516474 4085403 2335310 1739560 2014-10-30 20:52:10 2015-06-21 13:18:49 
469064 1613816 4692514 2335310 1739560 2015-01-10 12:29:30 2015-06-21 13:18:49 
469064 1631484 4728047 2335310 1739560 2015-01-23 19:49:30 2015-06-21 13:18:49 
469064 1700479 5413265 2335310 1739560 2015-04-16 15:01:08 2015-06-21 13:18:49 
469064 1702863 5416425 2335310 1739560 2015-04-22 00:07:01 2015-06-21 13:18:49 
**469064 1739560 5540728 2335310 1739560 2015-06-17 05:12:05 2015-06-21 13:18:49** 
469064 1911207 5818507 2335310 1739560 2015-12-04 07:53:33 2015-06-21 13:18:49 
469064 1940132 5828037 2335310 1739560 2015-12-19 03:24:25 2015-06-21 13:18:49

在**标记的行中，v.id和s.vio_id的值是匹配的，除了查询对于sivioId列的其他行返回null的匹配行有什么区别吗？

来源

2017-02-15 SURYA VISWANATHAN

你在找什么是CASE声明。

您可以根据结果行中的值选择要返回的值。在这种情况下，当s.vio_id!=v.id时，您将返回null。

SELECT v.pattern_id, v.id, v.pdb_id AS viocardId, p.pdb_id AS PID, 
    CASE WHEN s.vio_id=v.id THEN s.vio_id ELSE null END AS SiVioId, 
    r.date AS orcdate, s.created_date AS sivcreateddate 

FROM orc_orcviolation AS v 
LEFT JOIN orc_orcpattern AS p ON v.pattern_id = p.id 
LEFT JOIN siverify_siverifyverificationsite s 
    ON p.pdb_id = s.pattern_id and p.if_target = s.if_target 
LEFT JOIN orc_orccheck AS o ON v.check_id = o.id 
LEFT JOIN orc_orcrecord AS r ON o.record_id = r.id 
WHERE p.if_secure <> 1

您的问题的答案来自我的查询的SELECT子句。
我使用JOINs重写了您的查询，因为我发现查看表格之间的连接更容易。如果您不想使用连接，请随意使用答案的SELECT部分。

该查询应导致：

pattern_id id  viocardId PID  SiVioId orcdate    sivcreateddate 
469064  1205777 3024788 2335310 null 2014-05-02 16:14:32 2015-06-21 13:18:49 
469064  1241653 3097963 2335310 null 2014-05-24 17:07:55 2015-06-21 13:18:49 
469064  1309143 3393980 2335310 null 2014-07-19 17:49:11 2015-06-21 13:18:49 
469064  1514825 4079963 2335310 null 2014-10-29 14:07:58 2015-06-21 13:18:49 
469064  1516474 4085403 2335310 null 2014-10-30 20:52:10 2015-06-21 13:18:49 
469064  1613816 4692514 2335310 null 2015-01-10 12:29:30 2015-06-21 13:18:49 
469064  1631484 4728047 2335310 null 2015-01-23 19:49:30 2015-06-21 13:18:49 
469064  1700479 5413265 2335310 null 2015-04-16 15:01:08 2015-06-21 13:18:49 
469064  1702863 5416425 2335310 null 2015-04-22 00:07:01 2015-06-21 13:18:49 
469064  1739560 5540728 2335310 1739560 2015-06-17 05:12:05 2015-06-21 13:18:49 
469064  1911207 5818507 2335310 null 2015-12-04 07:53:33 2015-06-21 13:18:49 
469064  1940132 5828037 2335310 null 2015-12-19 03:24:25 2015-06-21 13:18:49

来源

2017-02-15 03:14:39

分配空值复制匹配行的查询

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