Question

我有一张88码的桌子。我正在编写一个简单的select语句，该语句不选择以10或18开头的代码

select distinct pcl_mun from exemptions.modiv_parcels_2015 
where (pcl_mun NOT LIKE '10%') or (pcl_mun NOT LIKE '18%')
order by pcl_mun

一个人会认为这可行，但是它会返回所有结果

"0233"
"0242"
"1001"
"1002"
"1003"
"1004"
"1005"
"1006"
"1012"
"1013"
"1014"
"1015"
"1018"
"1019"
"1020"
"1024"
"1025"
"1401"
"1402"
"1403"
"1406"
"1407"
"1408"
"1409"
"1412"
"1413"
"1414"
"1415"
"1418"
"1419"
"1420"
"1421"
"1422"
"1423"
"1424"
"1425"
"1426"
"1427"
"1428"
"1429"
"1431"
"1432"
"1433"
"1434"
"1435"
"1436"
"1437"
"1438"
"1439"
"1601"
"1609"
"1611"
"1613"
"1615"
"1801"
"1802"
"1803"
"1807"
"1815"
"1904"
"1906"
"1908"
"1909"
"1911"
"1912"
"1916"
"1918"
"1919"
"1922"
"2101"
"2102"
"2103"
"2105"
"2106"
"2107"
"2108"
"2110"
"2111"
"2112"
"2114"
"2115"
"2116"
"2117"
"2119"
"2120"
"2121"
"2122"
"2123"

如果我自己单独运行每个类似的子句，它们将返回正确的结果。我在这里做错了什么？

Answer 1

结合NOT LIKE时，应使用AND代替OR

select distinct pcl_mun 
from exemptions.modiv_parcels_2015 
where pcl_mun NOT LIKE '10%' 
  AND pcl_mun NOT LIKE '18%'
order by pcl_mun

这是一个逻辑上的事情，有时会引起混淆。

简化示例：

('18' NOT LIKE '10%') OR ('18' NOT LIKE '18%')  --> true OR false --> true
('18' NOT LIKE '10%') AND ('18' NOT LIKE '18%')  --> true AND false --> FALSE

('14' NOT LIKE '10%') OR ('14' NOT LIKE '18%')  --> true OR true --> TRUE
('14' NOT LIKE '10%') AND ('14' NOT LIKE '18%')  --> true AND true --> TRUE

因为否定LIKE的组合时会有所不同。
然后应使用OR。

NOT ('18' LIKE '10%' OR '18' LIKE '18%')  --> NOT(false OR true) --> FALSE
NOT ('18' LIKE '10%' AND '18' LIKE '18%')  --> NOT(false AND true) --> true

NOT ('14' LIKE '10%' OR '14' LIKE '18%')  --> NOT(false OR false) --> TRUE
NOT ('14' LIKE '10%' AND '14' LIKE '18%')  --> NOT(false AND false) --> TRUE

PostgreSQL的两个NOT LIKE子句返回错误的结果

1 个答案: